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Allow hints to be placed anywhere in query
[pghintplan/pg_hint_plan.git] / pg_hint_plan.c
index f4636d2..0852f56 100644 (file)
@@ -1,44 +1,68 @@
 /*-------------------------------------------------------------------------
  *
  * pg_hint_plan.c
- *               do instructions or hints to the planner using C-style block comments
- *               of the SQL.
+ *               hinting on how to execute a query for PostgreSQL
  *
- * Copyright (c) 2012, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
+ * Copyright (c) 2012-2021, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
  *
  *-------------------------------------------------------------------------
  */
+#include <string.h>
+
 #include "postgres.h"
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/relation.h"
+#include "catalog/pg_collation.h"
+#include "catalog/pg_index.h"
 #include "commands/prepare.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "nodes/nodeFuncs.h"
+#include "nodes/params.h"
+#include "optimizer/appendinfo.h"
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
 #include "optimizer/geqo.h"
 #include "optimizer/joininfo.h"
+#include "optimizer/optimizer.h"
 #include "optimizer/pathnode.h"
 #include "optimizer/paths.h"
 #include "optimizer/plancat.h"
 #include "optimizer/planner.h"
 #include "optimizer/prep.h"
 #include "optimizer/restrictinfo.h"
+#include "parser/analyze.h"
+#include "parser/parsetree.h"
 #include "parser/scansup.h"
+#include "partitioning/partbounds.h"
 #include "tcop/utility.h"
+#include "utils/builtins.h"
+#include "utils/float.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
-#if PG_VERSION_NUM >= 90200
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+#include "utils/syscache.h"
+#include "utils/resowner.h"
+
 #include "catalog/pg_class.h"
-#endif
+
+#include "executor/spi.h"
+#include "catalog/pg_type.h"
+
+#include "plpgsql.h"
+
+/* partially copied from pg_stat_statements */
+#include "normalize_query.h"
+
+/* PostgreSQL */
+#include "access/htup_details.h"
 
 #ifdef PG_MODULE_MAGIC
 PG_MODULE_MAGIC;
 #endif
 
-#if PG_VERSION_NUM < 90100
-#error unsupported PostgreSQL version
-#endif
-
 #define BLOCK_COMMENT_START            "/*"
 #define BLOCK_COMMENT_END              "*/"
 #define HINT_COMMENT_KEYWORD   "+"
@@ -48,16 +72,19 @@ PG_MODULE_MAGIC;
 /* hint keywords */
 #define HINT_SEQSCAN                   "SeqScan"
 #define HINT_INDEXSCAN                 "IndexScan"
+#define HINT_INDEXSCANREGEXP   "IndexScanRegexp"
 #define HINT_BITMAPSCAN                        "BitmapScan"
+#define HINT_BITMAPSCANREGEXP  "BitmapScanRegexp"
 #define HINT_TIDSCAN                   "TidScan"
 #define HINT_NOSEQSCAN                 "NoSeqScan"
 #define HINT_NOINDEXSCAN               "NoIndexScan"
 #define HINT_NOBITMAPSCAN              "NoBitmapScan"
 #define HINT_NOTIDSCAN                 "NoTidScan"
-#if PG_VERSION_NUM >= 90200
 #define HINT_INDEXONLYSCAN             "IndexOnlyScan"
+#define HINT_INDEXONLYSCANREGEXP       "IndexOnlyScanRegexp"
 #define HINT_NOINDEXONLYSCAN   "NoIndexOnlyScan"
-#endif
+#define HINT_PARALLEL                  "Parallel"
+
 #define HINT_NESTLOOP                  "NestLoop"
 #define HINT_MERGEJOIN                 "MergeJoin"
 #define HINT_HASHJOIN                  "HashJoin"
@@ -66,13 +93,19 @@ PG_MODULE_MAGIC;
 #define HINT_NOHASHJOIN                        "NoHashJoin"
 #define HINT_LEADING                   "Leading"
 #define HINT_SET                               "Set"
+#define HINT_ROWS                              "Rows"
+#define HINT_MEMOIZE                   "Memoize"
+#define HINT_NOMEMOIZE                 "NoMemoize"
 
 #define HINT_ARRAY_DEFAULT_INITSIZE 8
 
-#define hint_ereport(str, detail) \
-       ereport(pg_hint_plan_parse_messages, \
-                       (errmsg("hint syntax error at or near \"%s\"", (str)), \
-                        errdetail detail))
+#define hint_ereport(str, detail) hint_parse_ereport(str, detail)
+#define hint_parse_ereport(str, detail) \
+       do { \
+               ereport(pg_hint_plan_parse_message_level,               \
+                       (errmsg("pg_hint_plan: hint syntax error at or near \"%s\"", (str)), \
+                        errdetail detail)); \
+       } while(0)
 
 #define skip_space(str) \
        while (isspace(*str)) \
@@ -84,26 +117,20 @@ enum
        ENABLE_INDEXSCAN = 0x02,
        ENABLE_BITMAPSCAN = 0x04,
        ENABLE_TIDSCAN = 0x08,
-#if PG_VERSION_NUM >= 90200
        ENABLE_INDEXONLYSCAN = 0x10
-#endif
 } SCAN_TYPE_BITS;
 
 enum
 {
        ENABLE_NESTLOOP = 0x01,
        ENABLE_MERGEJOIN = 0x02,
-       ENABLE_HASHJOIN = 0x04
+       ENABLE_HASHJOIN = 0x04,
+       ENABLE_MEMOIZE  = 0x08
 } JOIN_TYPE_BITS;
 
-#if PG_VERSION_NUM >= 90200
 #define ENABLE_ALL_SCAN (ENABLE_SEQSCAN | ENABLE_INDEXSCAN | \
                                                 ENABLE_BITMAPSCAN | ENABLE_TIDSCAN | \
                                                 ENABLE_INDEXONLYSCAN)
-#else
-#define ENABLE_ALL_SCAN (ENABLE_SEQSCAN | ENABLE_INDEXSCAN | \
-                                                ENABLE_BITMAPSCAN | ENABLE_TIDSCAN)
-#endif
 #define ENABLE_ALL_JOIN (ENABLE_NESTLOOP | ENABLE_MERGEJOIN | ENABLE_HASHJOIN)
 #define DISABLE_ALL_SCAN 0
 #define DISABLE_ALL_JOIN 0
@@ -113,27 +140,44 @@ typedef enum HintKeyword
 {
        HINT_KEYWORD_SEQSCAN,
        HINT_KEYWORD_INDEXSCAN,
+       HINT_KEYWORD_INDEXSCANREGEXP,
        HINT_KEYWORD_BITMAPSCAN,
+       HINT_KEYWORD_BITMAPSCANREGEXP,
        HINT_KEYWORD_TIDSCAN,
        HINT_KEYWORD_NOSEQSCAN,
        HINT_KEYWORD_NOINDEXSCAN,
        HINT_KEYWORD_NOBITMAPSCAN,
        HINT_KEYWORD_NOTIDSCAN,
-#if PG_VERSION_NUM >= 90200
        HINT_KEYWORD_INDEXONLYSCAN,
+       HINT_KEYWORD_INDEXONLYSCANREGEXP,
        HINT_KEYWORD_NOINDEXONLYSCAN,
-#endif
+
        HINT_KEYWORD_NESTLOOP,
        HINT_KEYWORD_MERGEJOIN,
        HINT_KEYWORD_HASHJOIN,
        HINT_KEYWORD_NONESTLOOP,
        HINT_KEYWORD_NOMERGEJOIN,
        HINT_KEYWORD_NOHASHJOIN,
+
        HINT_KEYWORD_LEADING,
        HINT_KEYWORD_SET,
+       HINT_KEYWORD_ROWS,
+       HINT_KEYWORD_PARALLEL,
+       HINT_KEYWORD_MEMOIZE,
+       HINT_KEYWORD_NOMEMOIZE,
+
        HINT_KEYWORD_UNRECOGNIZED
 } HintKeyword;
 
+#define SCAN_HINT_ACCEPTS_INDEX_NAMES(kw) \
+       (kw == HINT_KEYWORD_INDEXSCAN ||                        \
+        kw == HINT_KEYWORD_INDEXSCANREGEXP ||          \
+        kw == HINT_KEYWORD_INDEXONLYSCAN ||            \
+        kw == HINT_KEYWORD_INDEXONLYSCANREGEXP ||      \
+        kw == HINT_KEYWORD_BITMAPSCAN ||                               \
+        kw == HINT_KEYWORD_BITMAPSCANREGEXP)
+
+
 typedef struct Hint Hint;
 typedef struct HintState HintState;
 
@@ -141,26 +185,38 @@ typedef Hint *(*HintCreateFunction) (const char *hint_str,
                                                                         const char *keyword,
                                                                         HintKeyword hint_keyword);
 typedef void (*HintDeleteFunction) (Hint *hint);
-typedef void (*HintDumpFunction) (Hint *hint, StringInfo buf);
+typedef void (*HintDescFunction) (Hint *hint, StringInfo buf, bool nolf);
 typedef int (*HintCmpFunction) (const Hint *a, const Hint *b);
 typedef const char *(*HintParseFunction) (Hint *hint, HintState *hstate,
                                                                                  Query *parse, const char *str);
 
 /* hint types */
-#define NUM_HINT_TYPE  4
 typedef enum HintType
 {
        HINT_TYPE_SCAN_METHOD,
        HINT_TYPE_JOIN_METHOD,
        HINT_TYPE_LEADING,
-       HINT_TYPE_SET
+       HINT_TYPE_SET,
+       HINT_TYPE_ROWS,
+       HINT_TYPE_PARALLEL,
+       HINT_TYPE_MEMOIZE,
+
+       NUM_HINT_TYPE
 } HintType;
 
+typedef enum HintTypeBitmap
+{
+       HINT_BM_SCAN_METHOD = 1,
+       HINT_BM_PARALLEL = 2
+} HintTypeBitmap;
+
 static const char *HintTypeName[] = {
        "scan method",
        "join method",
        "leading",
-       "set"
+       "set",
+       "rows",
+       "parallel"
 };
 
 /* hint status */
@@ -176,6 +232,21 @@ typedef enum HintStatus
 #define hint_state_enabled(hint) ((hint)->base.state == HINT_STATE_NOTUSED || \
                                                                  (hint)->base.state == HINT_STATE_USED)
 
+static unsigned int qno = 0;
+static unsigned int msgqno = 0;
+static char qnostr[32];
+static const char *current_hint_str = NULL;
+
+/*
+ * We can utilize in-core generated jumble state in post_parse_analyze_hook.
+ * On the other hand there's a case where we're forced to get hints in
+ * planner_hook, where we don't have a jumble state.  If we a query had not a
+ * hint, we need to try to retrieve hints twice or more for one query, which is
+ * the quite common case.  To avoid such case, this variables is set true when
+ * we *try* hint retrieval.
+ */
+static bool current_hint_retrieved = false;
+
 /* common data for all hints. */
 struct Hint
 {
@@ -185,7 +256,7 @@ struct Hint
        HintType                        type;
        HintStatus                      state;
        HintDeleteFunction      delete_func;
-       HintDumpFunction        dump_func;
+       HintDescFunction        desc_func;
        HintCmpFunction         cmp_func;
        HintParseFunction       parse_func;
 };
@@ -196,24 +267,46 @@ typedef struct ScanMethodHint
        Hint                    base;
        char               *relname;
        List               *indexnames;
+       bool                    regexp;
        unsigned char   enforce_mask;
 } ScanMethodHint;
 
+typedef struct ParentIndexInfo
+{
+       bool            indisunique;
+       Oid                     method;
+       List       *column_names;
+       char       *expression_str;
+       Oid                *indcollation;
+       Oid                *opclass;
+       int16      *indoption;
+       char       *indpred_str;
+} ParentIndexInfo;
+
 /* join method hints */
 typedef struct JoinMethodHint
 {
        Hint                    base;
        int                             nrels;
+       int                             inner_nrels;
        char              **relnames;
        unsigned char   enforce_mask;
        Relids                  joinrelids;
+       Relids                  inner_joinrelids;
 } JoinMethodHint;
 
 /* join order hints */
+typedef struct OuterInnerRels
+{
+       char   *relation;
+       List   *outer_inner_pair;
+} OuterInnerRels;
+
 typedef struct LeadingHint
 {
-       Hint    base;
-       List   *relations;              /* relation names specified in Leading hint */
+       Hint                    base;
+       List               *relations;  /* relation names specified in Leading hint */
+       OuterInnerRels *outer_inner;
 } LeadingHint;
 
 /* change a run-time parameter hints */
@@ -225,6 +318,36 @@ typedef struct SetHint
        List   *words;
 } SetHint;
 
+/* rows hints */
+typedef enum RowsValueType {
+       RVT_ABSOLUTE,           /* Rows(... #1000) */
+       RVT_ADD,                        /* Rows(... +1000) */
+       RVT_SUB,                        /* Rows(... -1000) */
+       RVT_MULTI,                      /* Rows(... *1.2) */
+} RowsValueType;
+typedef struct RowsHint
+{
+       Hint                    base;
+       int                             nrels;
+       int                             inner_nrels;
+       char              **relnames;
+       Relids                  joinrelids;
+       Relids                  inner_joinrelids;
+       char               *rows_str;
+       RowsValueType   value_type;
+       double                  rows;
+} RowsHint;
+
+/* parallel hints */
+typedef struct ParallelHint
+{
+       Hint                    base;
+       char               *relname;
+       char               *nworkers_str;       /* original string of nworkers */
+       int                             nworkers;               /* num of workers specified by Worker */
+       bool                    force_parallel; /* force parallel scan */
+} ParallelHint;
+
 /*
  * Describes a context of hint processing.
  */
@@ -242,21 +365,33 @@ struct HintState
 
        /* for scan method hints */
        ScanMethodHint **scan_hints;            /* parsed scan hints */
-       int                             init_scan_mask;         /* initial value scan parameter */
-       Index                   parent_relid;           /* inherit parent table relid */
-       ScanMethodHint *parent_hint;            /* inherit parent table scan hint */
 
-       /* for join method hints */
+       /* Initial values of parameters  */
+       int                             init_scan_mask;         /* enable_* mask */
+       int                             init_nworkers;          /* max_parallel_workers_per_gather */
+       /* min_parallel_table_scan_size*/
+       int                             init_min_para_tablescan_size;
+       /* min_parallel_index_scan_size*/
+       int                             init_min_para_indexscan_size;
+       double                  init_paratup_cost;      /* parallel_tuple_cost */
+       double                  init_parasetup_cost;/* parallel_setup_cost */
+
+       PlannerInfo        *current_root;               /* PlannerInfo for the followings */
+       Index                   parent_relid;           /* inherit parent of table relid */
+       ScanMethodHint *parent_scan_hint;       /* scan hint for the parent */
+       ParallelHint   *parent_parallel_hint; /* parallel hint for the parent */
+       List               *parent_index_infos; /* list of parent table's index */
+
        JoinMethodHint **join_hints;            /* parsed join hints */
        int                             init_join_mask;         /* initial value join parameter */
        List              **join_hint_level;
-
-       /* for Leading hint */
-       LeadingHint        *leading_hint;               /* parsed last specified Leading hint */
-
-       /* for Set hints */
+       List              **memoize_hint_level;
+       LeadingHint       **leading_hint;               /* parsed Leading hints */
        SetHint           **set_hints;                  /* parsed Set hints */
        GucContext              context;                        /* which GUC parameters can we set? */
+       RowsHint          **rows_hints;                 /* parsed Rows hints */
+       ParallelHint  **parallel_hints;         /* parsed Parallel hints */
+       JoinMethodHint **memoize_hints;         /* parsed Memoize hints */
 };
 
 /*
@@ -269,6 +404,9 @@ typedef struct HintParser
        HintKeyword                     hint_keyword;
 } HintParser;
 
+static bool enable_hint_table_check(bool *newval, void **extra, GucSource source);
+static void assign_enable_hint_table(bool newval, void *extra);
+
 /* Module callbacks */
 void           _PG_init(void);
 void           _PG_fini(void);
@@ -276,77 +414,131 @@ void             _PG_fini(void);
 static void push_hint(HintState *hstate);
 static void pop_hint(void);
 
-static void pg_hint_plan_ProcessUtility(Node *parsetree,
-                                                                               const char *queryString,
-                                                                               ParamListInfo params, bool isTopLevel,
-                                                                               DestReceiver *dest,
-                                                                               char *completionTag);
-static PlannedStmt *pg_hint_plan_planner(Query *parse, int cursorOptions,
+static void pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query,
+                                                                                       JumbleState *jstate);
+static PlannedStmt *pg_hint_plan_planner(Query *parse, const char *query_string,
+                                                                                int cursorOptions,
                                                                                 ParamListInfo boundParams);
-static void pg_hint_plan_get_relation_info(PlannerInfo *root,
-                                                                                  Oid relationObjectId,
-                                                                                  bool inhparent, RelOptInfo *rel);
 static RelOptInfo *pg_hint_plan_join_search(PlannerInfo *root,
                                                                                        int levels_needed,
                                                                                        List *initial_rels);
 
+/* Scan method hint callbacks */
 static Hint *ScanMethodHintCreate(const char *hint_str, const char *keyword,
                                                                  HintKeyword hint_keyword);
 static void ScanMethodHintDelete(ScanMethodHint *hint);
-static void ScanMethodHintDump(ScanMethodHint *hint, StringInfo buf);
+static void ScanMethodHintDesc(ScanMethodHint *hint, StringInfo buf, bool nolf);
 static int ScanMethodHintCmp(const ScanMethodHint *a, const ScanMethodHint *b);
 static const char *ScanMethodHintParse(ScanMethodHint *hint, HintState *hstate,
                                                                           Query *parse, const char *str);
+
+/* Join method hint callbacks */
 static Hint *JoinMethodHintCreate(const char *hint_str, const char *keyword,
                                                                  HintKeyword hint_keyword);
 static void JoinMethodHintDelete(JoinMethodHint *hint);
-static void JoinMethodHintDump(JoinMethodHint *hint, StringInfo buf);
+static void JoinMethodHintDesc(JoinMethodHint *hint, StringInfo buf, bool nolf);
 static int JoinMethodHintCmp(const JoinMethodHint *a, const JoinMethodHint *b);
 static const char *JoinMethodHintParse(JoinMethodHint *hint, HintState *hstate,
                                                                           Query *parse, const char *str);
+
+/* Leading hint callbacks */
 static Hint *LeadingHintCreate(const char *hint_str, const char *keyword,
                                                           HintKeyword hint_keyword);
 static void LeadingHintDelete(LeadingHint *hint);
-static void LeadingHintDump(LeadingHint *hint, StringInfo buf);
+static void LeadingHintDesc(LeadingHint *hint, StringInfo buf, bool nolf);
 static int LeadingHintCmp(const LeadingHint *a, const LeadingHint *b);
 static const char *LeadingHintParse(LeadingHint *hint, HintState *hstate,
                                                                        Query *parse, const char *str);
+
+/* Set hint callbacks */
 static Hint *SetHintCreate(const char *hint_str, const char *keyword,
                                                   HintKeyword hint_keyword);
 static void SetHintDelete(SetHint *hint);
-static void SetHintDump(SetHint *hint, StringInfo buf);
+static void SetHintDesc(SetHint *hint, StringInfo buf, bool nolf);
 static int SetHintCmp(const SetHint *a, const SetHint *b);
 static const char *SetHintParse(SetHint *hint, HintState *hstate, Query *parse,
                                                                const char *str);
 
+/* Rows hint callbacks */
+static Hint *RowsHintCreate(const char *hint_str, const char *keyword,
+                                                       HintKeyword hint_keyword);
+static void RowsHintDelete(RowsHint *hint);
+static void RowsHintDesc(RowsHint *hint, StringInfo buf, bool nolf);
+static int RowsHintCmp(const RowsHint *a, const RowsHint *b);
+static const char *RowsHintParse(RowsHint *hint, HintState *hstate,
+                                                                Query *parse, const char *str);
+
+/* Parallel hint callbacks */
+static Hint *ParallelHintCreate(const char *hint_str, const char *keyword,
+                                                               HintKeyword hint_keyword);
+static void ParallelHintDelete(ParallelHint *hint);
+static void ParallelHintDesc(ParallelHint *hint, StringInfo buf, bool nolf);
+static int ParallelHintCmp(const ParallelHint *a, const ParallelHint *b);
+static const char *ParallelHintParse(ParallelHint *hint, HintState *hstate,
+                                                                        Query *parse, const char *str);
+
+static Hint *MemoizeHintCreate(const char *hint_str, const char *keyword,
+                                                          HintKeyword hint_keyword);
+
+static void quote_value(StringInfo buf, const char *value);
+
+static const char *parse_quoted_value(const char *str, char **word,
+                                                                         bool truncate);
+
 RelOptInfo *pg_hint_plan_standard_join_search(PlannerInfo *root,
                                                                                          int levels_needed,
                                                                                          List *initial_rels);
 void pg_hint_plan_join_search_one_level(PlannerInfo *root, int level);
+void pg_hint_plan_set_rel_pathlist(PlannerInfo * root, RelOptInfo *rel,
+                                                                  Index rti, RangeTblEntry *rte);
+static void create_plain_partial_paths(PlannerInfo *root,
+                                                                                                       RelOptInfo *rel);
 static void make_rels_by_clause_joins(PlannerInfo *root, RelOptInfo *old_rel,
+                                                                         List *other_rels_list,
                                                                          ListCell *other_rels);
 static void make_rels_by_clauseless_joins(PlannerInfo *root,
                                                                                  RelOptInfo *old_rel,
-                                                                                 ListCell *other_rels);
+                                                                                 List *other_rels);
 static bool has_join_restriction(PlannerInfo *root, RelOptInfo *rel);
-static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
-                                                                       Index rti, RangeTblEntry *rte);
-#if PG_VERSION_NUM >= 90200
-static void generate_mergeappend_paths(PlannerInfo *root, RelOptInfo *rel,
-                                                  List *live_childrels,
-                                                  List *all_child_pathkeys);
-#endif
-static List *accumulate_append_subpath(List *subpaths, Path *path);
-#if PG_VERSION_NUM < 90200
-static void set_dummy_rel_pathlist(RelOptInfo *rel);
-#endif
+static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
+                                                                  RangeTblEntry *rte);
 RelOptInfo *pg_hint_plan_make_join_rel(PlannerInfo *root, RelOptInfo *rel1,
                                                                           RelOptInfo *rel2);
 
+static void pg_hint_plan_plpgsql_stmt_beg(PLpgSQL_execstate *estate,
+                                                                                 PLpgSQL_stmt *stmt);
+static void pg_hint_plan_plpgsql_stmt_end(PLpgSQL_execstate *estate,
+                                                                                 PLpgSQL_stmt *stmt);
+static void plpgsql_query_erase_callback(ResourceReleasePhase phase,
+                                                                                bool isCommit,
+                                                                                bool isTopLevel,
+                                                                                void *arg);
+static int set_config_option_noerror(const char *name, const char *value,
+                                                 GucContext context, GucSource source,
+                                                 GucAction action, bool changeVal, int elevel);
+static void setup_scan_method_enforcement(ScanMethodHint *scanhint,
+                                                                                 HintState *state);
+static int set_config_int32_option(const char *name, int32 value,
+                                                                       GucContext context);
+static int set_config_double_option(const char *name, double value,
+                                                                       GucContext context);
+
 /* GUC variables */
 static bool    pg_hint_plan_enable_hint = true;
-static bool    pg_hint_plan_debug_print = false;
-static int     pg_hint_plan_parse_messages = INFO;
+static int debug_level = 0;
+static int     pg_hint_plan_parse_message_level = INFO;
+static int     pg_hint_plan_debug_message_level = LOG;
+/* Default is off, to keep backward compatibility. */
+static bool    pg_hint_plan_enable_hint_table = false;
+static bool    pg_hint_plan_hints_anywhere = false;
+
+static int plpgsql_recurse_level = 0;          /* PLpgSQL recursion level            */
+static int recurse_level = 0;          /* recursion level incl. direct SPI calls */
+static int hint_inhibit_level = 0;                     /* Inhibit hinting if this is above 0 */
+                                                                                       /* (This could not be above 1)        */
+static int max_hint_nworkers = -1;             /* Maximum nworkers of Workers hints */
+
+static bool    hint_table_deactivated = false;
 
 static const struct config_enum_entry parse_messages_level_options[] = {
        {"debug", DEBUG2, true},
@@ -367,74 +559,108 @@ static const struct config_enum_entry parse_messages_level_options[] = {
        {NULL, 0, false}
 };
 
+static const struct config_enum_entry parse_debug_level_options[] = {
+       {"off", 0, false},
+       {"on", 1, false},
+       {"detailed", 2, false},
+       {"verbose", 3, false},
+       {"0", 0, true},
+       {"1", 1, true},
+       {"2", 2, true},
+       {"3", 3, true},
+       {"no", 0, true},
+       {"yes", 1, true},
+       {"false", 0, true},
+       {"true", 1, true},
+       {NULL, 0, false}
+};
+
 /* Saved hook values in case of unload */
-static ProcessUtility_hook_type prev_ProcessUtility = NULL;
+static post_parse_analyze_hook_type prev_post_parse_analyze_hook = NULL;
 static planner_hook_type prev_planner = NULL;
-static get_relation_info_hook_type prev_get_relation_info = NULL;
 static join_search_hook_type prev_join_search = NULL;
+static set_rel_pathlist_hook_type prev_set_rel_pathlist = NULL;
 
 /* Hold reference to currently active hint */
-static HintState *current_hint = NULL;
+static HintState *current_hint_state = NULL;
 
 /*
  * List of hint contexts.  We treat the head of the list as the Top of the
- * context stack, so current_hint always points the first element of this list.
+ * context stack, so current_hint_state always points the first element of this
+ * list.
  */
 static List *HintStateStack = NIL;
 
-/*
- * Holds statement name during executing EXECUTE command.  NULL for other
- * statements.
- */
-static char       *stmt_name = NULL;
-
 static const HintParser parsers[] = {
        {HINT_SEQSCAN, ScanMethodHintCreate, HINT_KEYWORD_SEQSCAN},
        {HINT_INDEXSCAN, ScanMethodHintCreate, HINT_KEYWORD_INDEXSCAN},
+       {HINT_INDEXSCANREGEXP, ScanMethodHintCreate, HINT_KEYWORD_INDEXSCANREGEXP},
        {HINT_BITMAPSCAN, ScanMethodHintCreate, HINT_KEYWORD_BITMAPSCAN},
+       {HINT_BITMAPSCANREGEXP, ScanMethodHintCreate,
+        HINT_KEYWORD_BITMAPSCANREGEXP},
        {HINT_TIDSCAN, ScanMethodHintCreate, HINT_KEYWORD_TIDSCAN},
        {HINT_NOSEQSCAN, ScanMethodHintCreate, HINT_KEYWORD_NOSEQSCAN},
        {HINT_NOINDEXSCAN, ScanMethodHintCreate, HINT_KEYWORD_NOINDEXSCAN},
        {HINT_NOBITMAPSCAN, ScanMethodHintCreate, HINT_KEYWORD_NOBITMAPSCAN},
        {HINT_NOTIDSCAN, ScanMethodHintCreate, HINT_KEYWORD_NOTIDSCAN},
-#if PG_VERSION_NUM >= 90200
        {HINT_INDEXONLYSCAN, ScanMethodHintCreate, HINT_KEYWORD_INDEXONLYSCAN},
+       {HINT_INDEXONLYSCANREGEXP, ScanMethodHintCreate,
+        HINT_KEYWORD_INDEXONLYSCANREGEXP},
        {HINT_NOINDEXONLYSCAN, ScanMethodHintCreate, HINT_KEYWORD_NOINDEXONLYSCAN},
-#endif
+
        {HINT_NESTLOOP, JoinMethodHintCreate, HINT_KEYWORD_NESTLOOP},
        {HINT_MERGEJOIN, JoinMethodHintCreate, HINT_KEYWORD_MERGEJOIN},
        {HINT_HASHJOIN, JoinMethodHintCreate, HINT_KEYWORD_HASHJOIN},
        {HINT_NONESTLOOP, JoinMethodHintCreate, HINT_KEYWORD_NONESTLOOP},
        {HINT_NOMERGEJOIN, JoinMethodHintCreate, HINT_KEYWORD_NOMERGEJOIN},
        {HINT_NOHASHJOIN, JoinMethodHintCreate, HINT_KEYWORD_NOHASHJOIN},
+
        {HINT_LEADING, LeadingHintCreate, HINT_KEYWORD_LEADING},
        {HINT_SET, SetHintCreate, HINT_KEYWORD_SET},
+       {HINT_ROWS, RowsHintCreate, HINT_KEYWORD_ROWS},
+       {HINT_PARALLEL, ParallelHintCreate, HINT_KEYWORD_PARALLEL},
+       {HINT_MEMOIZE, MemoizeHintCreate, HINT_KEYWORD_MEMOIZE},
+       {HINT_NOMEMOIZE, MemoizeHintCreate, HINT_KEYWORD_NOMEMOIZE},
+
        {NULL, NULL, HINT_KEYWORD_UNRECOGNIZED}
 };
 
+PLpgSQL_plugin  plugin_funcs = {
+       NULL,
+       NULL,
+       NULL,
+       pg_hint_plan_plpgsql_stmt_beg,
+       pg_hint_plan_plpgsql_stmt_end,
+       NULL,
+       NULL,
+};
+
 /*
  * Module load callbacks
  */
 void
 _PG_init(void)
 {
+       PLpgSQL_plugin  **var_ptr;
+
        /* Define custom GUC variables. */
        DefineCustomBoolVariable("pg_hint_plan.enable_hint",
                         "Force planner to use plans specified in the hint comment preceding to the query.",
                                                         NULL,
                                                         &pg_hint_plan_enable_hint,
                                                         true,
-                                                        PGC_USERSET,
+                                                    PGC_USERSET,
                                                         0,
                                                         NULL,
                                                         NULL,
                                                         NULL);
 
-       DefineCustomBoolVariable("pg_hint_plan.debug_print",
+       DefineCustomEnumVariable("pg_hint_plan.debug_print",
                                                         "Logs results of hint parsing.",
                                                         NULL,
-                                                        &pg_hint_plan_debug_print,
+                                                        &debug_level,
                                                         false,
+                                                        parse_debug_level_options,
                                                         PGC_USERSET,
                                                         0,
                                                         NULL,
@@ -444,7 +670,7 @@ _PG_init(void)
        DefineCustomEnumVariable("pg_hint_plan.parse_messages",
                                                         "Message level of parse errors.",
                                                         NULL,
-                                                        &pg_hint_plan_parse_messages,
+                                                        &pg_hint_plan_parse_message_level,
                                                         INFO,
                                                         parse_messages_level_options,
                                                         PGC_USERSET,
@@ -453,15 +679,57 @@ _PG_init(void)
                                                         NULL,
                                                         NULL);
 
+       DefineCustomEnumVariable("pg_hint_plan.message_level",
+                                                        "Message level of debug messages.",
+                                                        NULL,
+                                                        &pg_hint_plan_debug_message_level,
+                                                        LOG,
+                                                        parse_messages_level_options,
+                                                        PGC_USERSET,
+                                                        0,
+                                                        NULL,
+                                                        NULL,
+                                                        NULL);
+
+       DefineCustomBoolVariable("pg_hint_plan.enable_hint_table",
+                                                        "Let pg_hint_plan look up the hint table.",
+                                                        NULL,
+                                                        &pg_hint_plan_enable_hint_table,
+                                                        false,
+                                                        PGC_USERSET,
+                                                        0,
+                                                        enable_hint_table_check,
+                                                        assign_enable_hint_table,
+                                                        NULL);
+
+       DefineCustomBoolVariable("pg_hint_plan.hints_anywhere",
+                                                        "Read hints from anywhere in a query.",
+                                                        "This option lets pg_hint_plan ignore syntax so be cautious for false reads.",
+                                                        &pg_hint_plan_hints_anywhere,
+                                                        false,
+                                                        PGC_USERSET,
+                                                        0,
+                                                        NULL,
+                                                        NULL,
+                                                        NULL);
+
+       EmitWarningsOnPlaceholders("pg_hint_plan");
+
        /* Install hooks. */
-       prev_ProcessUtility = ProcessUtility_hook;
-       ProcessUtility_hook = pg_hint_plan_ProcessUtility;
+       prev_post_parse_analyze_hook = post_parse_analyze_hook;
+       post_parse_analyze_hook = pg_hint_plan_post_parse_analyze;
        prev_planner = planner_hook;
        planner_hook = pg_hint_plan_planner;
-       prev_get_relation_info = get_relation_info_hook;
-       get_relation_info_hook = pg_hint_plan_get_relation_info;
        prev_join_search = join_search_hook;
        join_search_hook = pg_hint_plan_join_search;
+       prev_set_rel_pathlist = set_rel_pathlist_hook;
+       set_rel_pathlist_hook = pg_hint_plan_set_rel_pathlist;
+
+       /* setup PL/pgSQL plugin hook */
+       var_ptr = (PLpgSQL_plugin **) find_rendezvous_variable("PLpgSQL_plugin");
+       *var_ptr = &plugin_funcs;
+
+       RegisterResourceReleaseCallback(plpgsql_query_erase_callback, NULL);
 }
 
 /*
@@ -471,11 +739,41 @@ _PG_init(void)
 void
 _PG_fini(void)
 {
+       PLpgSQL_plugin  **var_ptr;
+
        /* Uninstall hooks. */
-       ProcessUtility_hook = prev_ProcessUtility;
        planner_hook = prev_planner;
-       get_relation_info_hook = prev_get_relation_info;
        join_search_hook = prev_join_search;
+       set_rel_pathlist_hook = prev_set_rel_pathlist;
+
+       /* uninstall PL/pgSQL plugin hook */
+       var_ptr = (PLpgSQL_plugin **) find_rendezvous_variable("PLpgSQL_plugin");
+       *var_ptr = NULL;
+}
+
+static bool
+enable_hint_table_check(bool *newval, void **extra, GucSource source)
+{
+       if (*newval)
+       {
+               EnableQueryId();
+
+               if (!IsQueryIdEnabled())
+               {
+                       GUC_check_errmsg("table hint is not activated because queryid is not available");
+                       GUC_check_errhint("Set compute_query_id to on or auto to use hint table.");
+                       return false;
+               }
+       }
+
+       return true;
+}
+
+static void
+assign_enable_hint_table(bool newval, void *extra)
+{
+       if (!newval)
+               hint_table_deactivated = false;
 }
 
 /*
@@ -495,11 +793,12 @@ ScanMethodHintCreate(const char *hint_str, const char *keyword,
        hint->base.type = HINT_TYPE_SCAN_METHOD;
        hint->base.state = HINT_STATE_NOTUSED;
        hint->base.delete_func = (HintDeleteFunction) ScanMethodHintDelete;
-       hint->base.dump_func = (HintDumpFunction) ScanMethodHintDump;
+       hint->base.desc_func = (HintDescFunction) ScanMethodHintDesc;
        hint->base.cmp_func = (HintCmpFunction) ScanMethodHintCmp;
        hint->base.parse_func = (HintParseFunction) ScanMethodHintParse;
        hint->relname = NULL;
        hint->indexnames = NIL;
+       hint->regexp = false;
        hint->enforce_mask = 0;
 
        return (Hint *) hint;
@@ -530,13 +829,15 @@ JoinMethodHintCreate(const char *hint_str, const char *keyword,
        hint->base.type = HINT_TYPE_JOIN_METHOD;
        hint->base.state = HINT_STATE_NOTUSED;
        hint->base.delete_func = (HintDeleteFunction) JoinMethodHintDelete;
-       hint->base.dump_func = (HintDumpFunction) JoinMethodHintDump;
+       hint->base.desc_func = (HintDescFunction) JoinMethodHintDesc;
        hint->base.cmp_func = (HintCmpFunction) JoinMethodHintCmp;
        hint->base.parse_func = (HintParseFunction) JoinMethodHintParse;
        hint->nrels = 0;
+       hint->inner_nrels = 0;
        hint->relnames = NULL;
        hint->enforce_mask = 0;
        hint->joinrelids = NULL;
+       hint->inner_joinrelids = NULL;
 
        return (Hint *) hint;
 }
@@ -555,7 +856,9 @@ JoinMethodHintDelete(JoinMethodHint *hint)
                        pfree(hint->relnames[i]);
                pfree(hint->relnames);
        }
+
        bms_free(hint->joinrelids);
+       bms_free(hint->inner_joinrelids);
        pfree(hint);
 }
 
@@ -572,10 +875,11 @@ LeadingHintCreate(const char *hint_str, const char *keyword,
        hint->base.type = HINT_TYPE_LEADING;
        hint->base.state = HINT_STATE_NOTUSED;
        hint->base.delete_func = (HintDeleteFunction)LeadingHintDelete;
-       hint->base.dump_func = (HintDumpFunction) LeadingHintDump;
+       hint->base.desc_func = (HintDescFunction) LeadingHintDesc;
        hint->base.cmp_func = (HintCmpFunction) LeadingHintCmp;
        hint->base.parse_func = (HintParseFunction) LeadingHintParse;
        hint->relations = NIL;
+       hint->outer_inner = NULL;
 
        return (Hint *) hint;
 }
@@ -587,6 +891,8 @@ LeadingHintDelete(LeadingHint *hint)
                return;
 
        list_free_deep(hint->relations);
+       if (hint->outer_inner)
+               pfree(hint->outer_inner);
        pfree(hint);
 }
 
@@ -603,7 +909,7 @@ SetHintCreate(const char *hint_str, const char *keyword,
        hint->base.type = HINT_TYPE_SET;
        hint->base.state = HINT_STATE_NOTUSED;
        hint->base.delete_func = (HintDeleteFunction) SetHintDelete;
-       hint->base.dump_func = (HintDumpFunction) SetHintDump;
+       hint->base.desc_func = (HintDescFunction) SetHintDesc;
        hint->base.cmp_func = (HintCmpFunction) SetHintCmp;
        hint->base.parse_func = (HintParseFunction) SetHintParse;
        hint->name = NULL;
@@ -628,6 +934,106 @@ SetHintDelete(SetHint *hint)
        pfree(hint);
 }
 
+static Hint *
+RowsHintCreate(const char *hint_str, const char *keyword,
+                          HintKeyword hint_keyword)
+{
+       RowsHint *hint;
+
+       hint = palloc(sizeof(RowsHint));
+       hint->base.hint_str = hint_str;
+       hint->base.keyword = keyword;
+       hint->base.hint_keyword = hint_keyword;
+       hint->base.type = HINT_TYPE_ROWS;
+       hint->base.state = HINT_STATE_NOTUSED;
+       hint->base.delete_func = (HintDeleteFunction) RowsHintDelete;
+       hint->base.desc_func = (HintDescFunction) RowsHintDesc;
+       hint->base.cmp_func = (HintCmpFunction) RowsHintCmp;
+       hint->base.parse_func = (HintParseFunction) RowsHintParse;
+       hint->nrels = 0;
+       hint->inner_nrels = 0;
+       hint->relnames = NULL;
+       hint->joinrelids = NULL;
+       hint->inner_joinrelids = NULL;
+       hint->rows_str = NULL;
+       hint->value_type = RVT_ABSOLUTE;
+       hint->rows = 0;
+
+       return (Hint *) hint;
+}
+
+static void
+RowsHintDelete(RowsHint *hint)
+{
+       if (!hint)
+               return;
+
+       if (hint->relnames)
+       {
+               int     i;
+
+               for (i = 0; i < hint->nrels; i++)
+                       pfree(hint->relnames[i]);
+               pfree(hint->relnames);
+       }
+
+       bms_free(hint->joinrelids);
+       bms_free(hint->inner_joinrelids);
+       pfree(hint);
+}
+
+static Hint *
+ParallelHintCreate(const char *hint_str, const char *keyword,
+                                 HintKeyword hint_keyword)
+{
+       ParallelHint *hint;
+
+       hint = palloc(sizeof(ParallelHint));
+       hint->base.hint_str = hint_str;
+       hint->base.keyword = keyword;
+       hint->base.hint_keyword = hint_keyword;
+       hint->base.type = HINT_TYPE_PARALLEL;
+       hint->base.state = HINT_STATE_NOTUSED;
+       hint->base.delete_func = (HintDeleteFunction) ParallelHintDelete;
+       hint->base.desc_func = (HintDescFunction) ParallelHintDesc;
+       hint->base.cmp_func = (HintCmpFunction) ParallelHintCmp;
+       hint->base.parse_func = (HintParseFunction) ParallelHintParse;
+       hint->relname = NULL;
+       hint->nworkers = 0;
+       hint->nworkers_str = "0";
+
+       return (Hint *) hint;
+}
+
+static void
+ParallelHintDelete(ParallelHint *hint)
+{
+       if (!hint)
+               return;
+
+       if (hint->relname)
+               pfree(hint->relname);
+       pfree(hint);
+}
+
+
+static Hint *
+MemoizeHintCreate(const char *hint_str, const char *keyword,
+                                 HintKeyword hint_keyword)
+{
+       /*
+        * MemoizeHintCreate shares the same struct with JoinMethodHint and the
+        * only difference is the hint type.
+        */
+       JoinMethodHint *hint =
+               (JoinMethodHint *)JoinMethodHintCreate(hint_str, keyword, hint_keyword);
+
+       hint->base.type = HINT_TYPE_MEMOIZE;
+
+       return (Hint *) hint;
+}
+
+
 static HintState *
 HintStateCreate(void)
 {
@@ -641,14 +1047,25 @@ HintStateCreate(void)
        memset(hstate->num_hints, 0, sizeof(hstate->num_hints));
        hstate->scan_hints = NULL;
        hstate->init_scan_mask = 0;
+       hstate->init_nworkers = 0;
+       hstate->init_min_para_tablescan_size = 0;
+       hstate->init_min_para_indexscan_size = 0;
+       hstate->init_paratup_cost = 0;
+       hstate->init_parasetup_cost = 0;
+       hstate->current_root = NULL;
        hstate->parent_relid = 0;
-       hstate->parent_hint = NULL;
+       hstate->parent_scan_hint = NULL;
+       hstate->parent_parallel_hint = NULL;
+       hstate->parent_index_infos = NIL;
        hstate->join_hints = NULL;
        hstate->init_join_mask = 0;
        hstate->join_hint_level = NULL;
+       hstate->memoize_hint_level = NULL;
        hstate->leading_hint = NULL;
        hstate->context = superuser() ? PGC_SUSET : PGC_USERSET;
        hstate->set_hints = NULL;
+       hstate->rows_hints = NULL;
+       hstate->parallel_hints = NULL;
 
        return hstate;
 }
@@ -668,21 +1085,22 @@ HintStateDelete(HintState *hstate)
                hstate->all_hints[i]->delete_func(hstate->all_hints[i]);
        if (hstate->all_hints)
                pfree(hstate->all_hints);
+       if (hstate->parent_index_infos)
+               list_free(hstate->parent_index_infos);
 }
 
 /*
- * dump functions
+ * Copy given value into buf, with quoting with '"' if necessary.
  */
-
 static void
-dump_quote_value(StringInfo buf, const char *value)
+quote_value(StringInfo buf, const char *value)
 {
        bool            need_quote = false;
        const char *str;
 
        for (str = value; *str != '\0'; str++)
        {
-               if (isspace(*str) || *str == ')' || *str == '"')
+               if (isspace(*str) || *str == '(' || *str == ')' || *str == '"')
                {
                        need_quote = true;
                        appendStringInfoCharMacro(buf, '"');
@@ -703,65 +1121,103 @@ dump_quote_value(StringInfo buf, const char *value)
 }
 
 static void
-ScanMethodHintDump(ScanMethodHint *hint, StringInfo buf)
+ScanMethodHintDesc(ScanMethodHint *hint, StringInfo buf, bool nolf)
 {
        ListCell   *l;
 
        appendStringInfo(buf, "%s(", hint->base.keyword);
        if (hint->relname != NULL)
        {
-               dump_quote_value(buf, hint->relname);
+               quote_value(buf, hint->relname);
                foreach(l, hint->indexnames)
                {
                        appendStringInfoCharMacro(buf, ' ');
-                       dump_quote_value(buf, (char *) lfirst(l));
+                       quote_value(buf, (char *) lfirst(l));
                }
        }
-       appendStringInfoString(buf, ")\n");
+       appendStringInfoString(buf, ")");
+       if (!nolf)
+               appendStringInfoChar(buf, '\n');
 }
 
 static void
-JoinMethodHintDump(JoinMethodHint *hint, StringInfo buf)
+JoinMethodHintDesc(JoinMethodHint *hint, StringInfo buf, bool nolf)
 {
        int     i;
 
        appendStringInfo(buf, "%s(", hint->base.keyword);
        if (hint->relnames != NULL)
        {
-               dump_quote_value(buf, hint->relnames[0]);
+               quote_value(buf, hint->relnames[0]);
                for (i = 1; i < hint->nrels; i++)
                {
                        appendStringInfoCharMacro(buf, ' ');
-                       dump_quote_value(buf, hint->relnames[i]);
+                       quote_value(buf, hint->relnames[i]);
                }
        }
-       appendStringInfoString(buf, ")\n");
-
+       appendStringInfoString(buf, ")");
+       if (!nolf)
+               appendStringInfoChar(buf, '\n');
 }
 
 static void
-LeadingHintDump(LeadingHint *hint, StringInfo buf)
+OuterInnerDesc(OuterInnerRels *outer_inner, StringInfo buf)
 {
-       bool            is_first;
-       ListCell   *l;
+       if (outer_inner->relation == NULL)
+       {
+               bool            is_first;
+               ListCell   *l;
+
+               is_first = true;
+
+               appendStringInfoCharMacro(buf, '(');
+               foreach(l, outer_inner->outer_inner_pair)
+               {
+                       if (is_first)
+                               is_first = false;
+                       else
+                               appendStringInfoCharMacro(buf, ' ');
+
+                       OuterInnerDesc(lfirst(l), buf);
+               }
+
+               appendStringInfoCharMacro(buf, ')');
+       }
+       else
+               quote_value(buf, outer_inner->relation);
+}
 
+static void
+LeadingHintDesc(LeadingHint *hint, StringInfo buf, bool nolf)
+{
        appendStringInfo(buf, "%s(", HINT_LEADING);
-       is_first = true;
-       foreach(l, hint->relations)
+       if (hint->outer_inner == NULL)
        {
-               if (is_first)
-                       is_first = false;
-               else
-                       appendStringInfoCharMacro(buf, ' ');
+               ListCell   *l;
+               bool            is_first;
+
+               is_first = true;
+
+               foreach(l, hint->relations)
+               {
+                       if (is_first)
+                               is_first = false;
+                       else
+                               appendStringInfoCharMacro(buf, ' ');
 
-               dump_quote_value(buf, (char *) lfirst(l));
+                       quote_value(buf, (char *) lfirst(l));
+               }
        }
+       else
+               OuterInnerDesc(hint->outer_inner, buf);
 
-       appendStringInfoString(buf, ")\n");
+       appendStringInfoString(buf, ")");
+       if (!nolf)
+               appendStringInfoChar(buf, '\n');
 }
 
 static void
-SetHintDump(SetHint *hint, StringInfo buf)
+SetHintDesc(SetHint *hint, StringInfo buf, bool nolf)
 {
        bool            is_first = true;
        ListCell   *l;
@@ -774,27 +1230,87 @@ SetHintDump(SetHint *hint, StringInfo buf)
                else
                        appendStringInfoCharMacro(buf, ' ');
 
-               dump_quote_value(buf, (char *) lfirst(l));
+               quote_value(buf, (char *) lfirst(l));
        }
-       appendStringInfo(buf, ")\n");
+       appendStringInfo(buf, ")");
+       if (!nolf)
+               appendStringInfoChar(buf, '\n');
 }
 
 static void
-all_hint_dump(HintState *hstate, StringInfo buf, const char *title,
-                         HintStatus state)
+RowsHintDesc(RowsHint *hint, StringInfo buf, bool nolf)
 {
        int     i;
 
-       appendStringInfo(buf, "%s:\n", title);
+       appendStringInfo(buf, "%s(", hint->base.keyword);
+       if (hint->relnames != NULL)
+       {
+               quote_value(buf, hint->relnames[0]);
+               for (i = 1; i < hint->nrels; i++)
+               {
+                       appendStringInfoCharMacro(buf, ' ');
+                       quote_value(buf, hint->relnames[i]);
+               }
+       }
+       if (hint->rows_str != NULL)
+               appendStringInfo(buf, " %s", hint->rows_str);
+       appendStringInfoString(buf, ")");
+       if (!nolf)
+               appendStringInfoChar(buf, '\n');
+}
+
+static void
+ParallelHintDesc(ParallelHint *hint, StringInfo buf, bool nolf)
+{
+       appendStringInfo(buf, "%s(", hint->base.keyword);
+       if (hint->relname != NULL)
+       {
+               quote_value(buf, hint->relname);
+
+               /* number of workers  */
+               appendStringInfoCharMacro(buf, ' ');
+               quote_value(buf, hint->nworkers_str);
+               /* application mode of num of workers */
+               appendStringInfoCharMacro(buf, ' ');
+               appendStringInfoString(buf,
+                                                          (hint->force_parallel ? "hard" : "soft"));
+       }
+       appendStringInfoString(buf, ")");
+       if (!nolf)
+               appendStringInfoChar(buf, '\n');
+}
+
+/*
+ * Append string which represents all hints in a given state to buf, with
+ * preceding title with them.
+ */
+static void
+desc_hint_in_state(HintState *hstate, StringInfo buf, const char *title,
+                                  HintStatus state, bool nolf)
+{
+       int     i, nshown;
+
+       appendStringInfo(buf, "%s:", title);
+       if (!nolf)
+               appendStringInfoChar(buf, '\n');
+
+       nshown = 0;
        for (i = 0; i < hstate->nall_hints; i++)
        {
                if (hstate->all_hints[i]->state != state)
                        continue;
 
-               hstate->all_hints[i]->dump_func(hstate->all_hints[i], buf);
+               hstate->all_hints[i]->desc_func(hstate->all_hints[i], buf, nolf);
+               nshown++;
        }
+
+       if (nolf && nshown == 0)
+               appendStringInfoString(buf, "(none)");
 }
 
+/*
+ * Dump contents of given hstate to server log with log level LOG.
+ */
 static void
 HintStateDump(HintState *hstate)
 {
@@ -802,19 +1318,48 @@ HintStateDump(HintState *hstate)
 
        if (!hstate)
        {
-               elog(LOG, "pg_hint_plan:\nno hint");
+               elog(pg_hint_plan_debug_message_level, "pg_hint_plan:\nno hint");
                return;
        }
 
        initStringInfo(&buf);
 
        appendStringInfoString(&buf, "pg_hint_plan:\n");
-       all_hint_dump(hstate, &buf, "used hint", HINT_STATE_USED);
-       all_hint_dump(hstate, &buf, "not used hint", HINT_STATE_NOTUSED);
-       all_hint_dump(hstate, &buf, "duplication hint", HINT_STATE_DUPLICATION);
-       all_hint_dump(hstate, &buf, "error hint", HINT_STATE_ERROR);
+       desc_hint_in_state(hstate, &buf, "used hint", HINT_STATE_USED, false);
+       desc_hint_in_state(hstate, &buf, "not used hint", HINT_STATE_NOTUSED, false);
+       desc_hint_in_state(hstate, &buf, "duplication hint", HINT_STATE_DUPLICATION, false);
+       desc_hint_in_state(hstate, &buf, "error hint", HINT_STATE_ERROR, false);
+
+       ereport(pg_hint_plan_debug_message_level,
+                       (errmsg ("%s", buf.data)));
+
+       pfree(buf.data);
+}
+
+static void
+HintStateDump2(HintState *hstate)
+{
+       StringInfoData  buf;
+
+       if (!hstate)
+       {
+               elog(pg_hint_plan_debug_message_level,
+                        "pg_hint_plan%s: HintStateDump: no hint", qnostr);
+               return;
+       }
 
-       elog(LOG, "%s", buf.data);
+       initStringInfo(&buf);
+       appendStringInfo(&buf, "pg_hint_plan%s: HintStateDump: ", qnostr);
+       desc_hint_in_state(hstate, &buf, "{used hints", HINT_STATE_USED, true);
+       desc_hint_in_state(hstate, &buf, "}, {not used hints", HINT_STATE_NOTUSED, true);
+       desc_hint_in_state(hstate, &buf, "}, {duplicate hints", HINT_STATE_DUPLICATION, true);
+       desc_hint_in_state(hstate, &buf, "}, {error hints", HINT_STATE_ERROR, true);
+       appendStringInfoChar(&buf, '}');
+
+       ereport(pg_hint_plan_debug_message_level,
+                       (errmsg("%s", buf.data),
+                        errhidestmt(true),
+                        errhidecontext(true)));
 
        pfree(buf.data);
 }
@@ -869,12 +1414,36 @@ SetHintCmp(const SetHint *a, const SetHint *b)
 }
 
 static int
-HintCmp(const void *a, const void *b)
+RowsHintCmp(const RowsHint *a, const RowsHint *b)
 {
-       const Hint *hinta = *((const Hint **) a);
-       const Hint *hintb = *((const Hint **) b);
+       int     i;
 
-       if (hinta->type != hintb->type)
+       if (a->nrels != b->nrels)
+               return a->nrels - b->nrels;
+
+       for (i = 0; i < a->nrels; i++)
+       {
+               int     result;
+               if ((result = RelnameCmp(&a->relnames[i], &b->relnames[i])) != 0)
+                       return result;
+       }
+
+       return 0;
+}
+
+static int
+ParallelHintCmp(const ParallelHint *a, const ParallelHint *b)
+{
+       return RelnameCmp(&a->relname, &b->relname);
+}
+
+static int
+HintCmp(const void *a, const void *b)
+{
+       const Hint *hinta = *((const Hint **) a);
+       const Hint *hintb = *((const Hint **) b);
+
+       if (hinta->type != hintb->type)
                return hinta->type - hintb->type;
        if (hinta->state == HINT_STATE_ERROR)
                return -1;
@@ -943,7 +1512,7 @@ skip_parenthesis(const char *str, char parenthesis)
  * Parsed token is truncated within NAMEDATALEN-1 bytes, when truncate is true.
  */
 static const char *
-parse_quote_value(const char *str, char **word, bool truncate)
+parse_quoted_value(const char *str, char **word, bool truncate)
 {
        StringInfoData  buf;
        bool                    in_quote;
@@ -989,7 +1558,8 @@ parse_quote_value(const char *str, char **word, bool truncate)
                                        break;
                        }
                }
-               else if (isspace(*str) || *str == ')' || *str == '"' || *str == '\0')
+               else if (isspace(*str) || *str == '(' || *str == ')' || *str == '"' ||
+                                *str == '\0')
                        break;
 
                appendStringInfoCharMacro(&buf, *str++);
@@ -1013,8 +1583,104 @@ parse_quote_value(const char *str, char **word, bool truncate)
        return str;
 }
 
+static OuterInnerRels *
+OuterInnerRelsCreate(char *name, List *outer_inner_list)
+{
+       OuterInnerRels *outer_inner;
+
+       outer_inner = palloc(sizeof(OuterInnerRels));
+       outer_inner->relation = name;
+       outer_inner->outer_inner_pair = outer_inner_list;
+
+       return outer_inner;
+}
+
+static const char *
+parse_parentheses_Leading_in(const char *str, OuterInnerRels **outer_inner)
+{
+       List   *outer_inner_pair = NIL;
+
+       if ((str = skip_parenthesis(str, '(')) == NULL)
+               return NULL;
+
+       skip_space(str);
+
+       /* Store words in parentheses into outer_inner_list. */
+       while(*str != ')' && *str != '\0')
+       {
+               OuterInnerRels *outer_inner_rels;
+
+               if (*str == '(')
+               {
+                       str = parse_parentheses_Leading_in(str, &outer_inner_rels);
+                       if (str == NULL)
+                               break;
+               }
+               else
+               {
+                       char   *name;
+
+                       if ((str = parse_quoted_value(str, &name, true)) == NULL)
+                               break;
+                       else
+                               outer_inner_rels = OuterInnerRelsCreate(name, NIL);
+               }
+
+               outer_inner_pair = lappend(outer_inner_pair, outer_inner_rels);
+               skip_space(str);
+       }
+
+       if (str == NULL ||
+               (str = skip_parenthesis(str, ')')) == NULL)
+       {
+               list_free(outer_inner_pair);
+               return NULL;
+       }
+
+       *outer_inner = OuterInnerRelsCreate(NULL, outer_inner_pair);
+
+       return str;
+}
+
+static const char *
+parse_parentheses_Leading(const char *str, List **name_list,
+       OuterInnerRels **outer_inner)
+{
+       char   *name;
+       bool    truncate = true;
+
+       if ((str = skip_parenthesis(str, '(')) == NULL)
+               return NULL;
+
+       skip_space(str);
+       if (*str =='(')
+       {
+               if ((str = parse_parentheses_Leading_in(str, outer_inner)) == NULL)
+                       return NULL;
+       }
+       else
+       {
+               /* Store words in parentheses into name_list. */
+               while(*str != ')' && *str != '\0')
+               {
+                       if ((str = parse_quoted_value(str, &name, truncate)) == NULL)
+                       {
+                               list_free(*name_list);
+                               return NULL;
+                       }
+
+                       *name_list = lappend(*name_list, name);
+                       skip_space(str);
+               }
+       }
+
+       if ((str = skip_parenthesis(str, ')')) == NULL)
+               return NULL;
+       return str;
+}
+
 static const char *
-parse_parentheses(const char *str, List **name_list, HintType type)
+parse_parentheses(const char *str, List **name_list, HintKeyword keyword)
 {
        char   *name;
        bool    truncate = true;
@@ -1027,7 +1693,7 @@ parse_parentheses(const char *str, List **name_list, HintType type)
        /* Store words in parentheses into name_list. */
        while(*str != ')' && *str != '\0')
        {
-               if ((str = parse_quote_value(str, &name, truncate)) == NULL)
+               if ((str = parse_quoted_value(str, &name, truncate)) == NULL)
                {
                        list_free(*name_list);
                        return NULL;
@@ -1036,7 +1702,10 @@ parse_parentheses(const char *str, List **name_list, HintType type)
                *name_list = lappend(*name_list, name);
                skip_space(str);
 
-               if (type == HINT_TYPE_SET)
+               if (keyword == HINT_KEYWORD_INDEXSCANREGEXP ||
+                       keyword == HINT_KEYWORD_INDEXONLYSCANREGEXP ||
+                       keyword == HINT_KEYWORD_BITMAPSCANREGEXP ||
+                       keyword == HINT_KEYWORD_SET)
                {
                        truncate = false;
                }
@@ -1070,7 +1739,7 @@ parse_hints(HintState *hstate, Query *parse, const char *str)
                        char   *keyword = parser->keyword;
                        Hint   *hint;
 
-                       if (strcasecmp(buf.data, keyword) != 0)
+                       if (pg_strcasecmp(buf.data, keyword) != 0)
                                continue;
 
                        hint = parser->create_func(head, keyword, parser->hint_keyword);
@@ -1121,41 +1790,138 @@ parse_hints(HintState *hstate, Query *parse, const char *str)
        pfree(buf.data);
 }
 
-/*
- * Do basic parsing of the query head comment.
+
+/* 
+ * Get hints from table by client-supplied query string and application name.
  */
-static HintState *
-parse_head_comment(Query *parse)
+static const char *
+get_hints_from_table(const char *client_query, const char *client_application)
 {
-       const char *p;
-       char       *head;
-       char       *tail;
-       int                     len;
-       int                     i;
-       HintState   *hstate;
+       const char *search_query =
+               "SELECT hints "
+               "  FROM hint_plan.hints "
+               " WHERE norm_query_string = $1 "
+               "   AND ( application_name = $2 "
+               "    OR application_name = '' ) "
+               " ORDER BY application_name DESC";
+       static SPIPlanPtr plan = NULL;
+       char   *hints = NULL;
+       Oid             argtypes[2] = { TEXTOID, TEXTOID };
+       Datum   values[2];
+       char    nulls[2] = {' ', ' '};
+       text   *qry;
+       text   *app;
 
-       /* get client-supplied query string. */
-       if (stmt_name)
+       PG_TRY();
        {
-               PreparedStatement  *entry;
+               bool snapshot_set = false;
+
+               hint_inhibit_level++;
+
+               if (!ActiveSnapshotSet())
+               {
+                       PushActiveSnapshot(GetTransactionSnapshot());
+                       snapshot_set = true;
+               }
+       
+               SPI_connect();
+       
+               if (plan == NULL)
+               {
+                       SPIPlanPtr      p;
+                       p = SPI_prepare(search_query, 2, argtypes);
+                       plan = SPI_saveplan(p);
+                       SPI_freeplan(p);
+               }
+       
+               qry = cstring_to_text(client_query);
+               app = cstring_to_text(client_application);
+               values[0] = PointerGetDatum(qry);
+               values[1] = PointerGetDatum(app);
+       
+               SPI_execute_plan(plan, values, nulls, true, 1);
+       
+               if (SPI_processed > 0)
+               {
+                       char    *buf;
+       
+                       hints = SPI_getvalue(SPI_tuptable->vals[0],
+                                                                SPI_tuptable->tupdesc, 1);
+                       /*
+                        * Here we use SPI_palloc to ensure that hints string is valid even
+                        * after SPI_finish call.  We can't use simple palloc because it
+                        * allocates memory in SPI's context and that context is deleted in
+                        * SPI_finish.
+                        */
+                       buf = SPI_palloc(strlen(hints) + 1);
+                       strcpy(buf, hints);
+                       hints = buf;
+               }
+       
+               SPI_finish();
+
+               if (snapshot_set)
+                       PopActiveSnapshot();
 
-               entry = FetchPreparedStatement(stmt_name, true);
-               p = entry->plansource->query_string;
+               hint_inhibit_level--;
        }
-       else
-               p = debug_query_string;
+       PG_CATCH();
+       {
+               hint_inhibit_level--;
+               PG_RE_THROW();
+       }
+       PG_END_TRY();
+
+       return hints;
+}
+
+/*
+ * Get hints from the head block comment in client-supplied query string.
+ */
+static const char *
+get_hints_from_comment(const char *p)
+{
+       const char *hint_head;
+       char       *head;
+       char       *tail;
+       int                     len;
 
        if (p == NULL)
                return NULL;
 
        /* extract query head comment. */
-       len = strlen(HINT_START);
-       skip_space(p);
-       if (strncmp(p, HINT_START, len))
+       hint_head = strstr(p, HINT_START);
+       if (hint_head == NULL)
                return NULL;
+       if (!pg_hint_plan_hints_anywhere)
+       {
+               for (;p < hint_head; p++)
+               {
+                       /*
+                        * Allow these characters precedes hint comment:
+                        *   - digits
+                        *   - alphabets which are in ASCII range
+                        *   - space, tabs and new-lines
+                        *   - underscores, for identifier
+                        *   - commas, for SELECT clause, EXPLAIN and PREPARE
+                        *   - parentheses, for EXPLAIN and PREPARE
+                        *
+                        * Note that we don't use isalpha() nor isalnum() in ctype.h here to
+                        * avoid behavior which depends on locale setting.
+                        */
+                       if (!(*p >= '0' && *p <= '9') &&
+                               !(*p >= 'A' && *p <= 'Z') &&
+                               !(*p >= 'a' && *p <= 'z') &&
+                               !isspace(*p) &&
+                               *p != '_' &&
+                               *p != ',' &&
+                               *p != '(' && *p != ')')
+                               return NULL;
+               }
+       }
 
-       head = (char *) p;
-       p += len;
+       head = (char *)hint_head;
+       p = head + strlen(HINT_START);
        skip_space(p);
 
        /* find hint end keyword. */
@@ -1179,8 +1945,28 @@ parse_head_comment(Query *parse)
        head[len] = '\0';
        p = head;
 
+       return p;
+}
+
+/*
+ * Parse hints that got, create hint struct from parse tree and parse hints.
+ */
+static HintState *
+create_hintstate(Query *parse, const char *hints)
+{
+       const char *p;
+       int                     i;
+       HintState   *hstate;
+
+       if (hints == NULL)
+               return NULL;
+
+       /* -1 means that no Parallel hint is specified. */
+       max_hint_nworkers = -1;
+
+       p = hints;
        hstate = HintStateCreate();
-       hstate->hint_str = head;
+       hstate->hint_str = (char *) hints;
 
        /* parse each hint. */
        parse_hints(hstate, parse, p);
@@ -1205,7 +1991,7 @@ parse_head_comment(Query *parse)
 
        /*
         * If an object (or a set of objects) has multiple hints of same hint-type,
-        * only the last hint is valid and others are igonred in planning.
+        * only the last hint is valid and others are ignored in planning.
         * Hints except the last are marked as 'duplicated' to remember the order.
         */
        for (i = 0; i < hstate->nall_hints - 1; i++)
@@ -1214,6 +2000,13 @@ parse_head_comment(Query *parse)
                Hint   *next_hint = hstate->all_hints[i + 1];
 
                /*
+                * Leading hint is marked as 'duplicated' in transform_join_hints.
+                */
+               if (cur_hint->type == HINT_TYPE_LEADING &&
+                       next_hint->type == HINT_TYPE_LEADING)
+                       continue;
+
+               /*
                 * Note that we need to pass addresses of hint pointers, because
                 * HintCmp is designed to sort array of Hint* by qsort.
                 */
@@ -1230,16 +2023,18 @@ parse_head_comment(Query *parse)
         * array which consists of all hints.
         */
        hstate->scan_hints = (ScanMethodHint **) hstate->all_hints;
-       hstate->join_hints = (JoinMethodHint **) hstate->all_hints +
-               hstate->num_hints[HINT_TYPE_SCAN_METHOD];
-       hstate->leading_hint = (LeadingHint *) hstate->all_hints[
-               hstate->num_hints[HINT_TYPE_SCAN_METHOD] +
-               hstate->num_hints[HINT_TYPE_JOIN_METHOD] +
-               hstate->num_hints[HINT_TYPE_LEADING] - 1];
-       hstate->set_hints = (SetHint **) hstate->all_hints +
-               hstate->num_hints[HINT_TYPE_SCAN_METHOD] +
-               hstate->num_hints[HINT_TYPE_JOIN_METHOD] +
-               hstate->num_hints[HINT_TYPE_LEADING];
+       hstate->join_hints = (JoinMethodHint **) (hstate->scan_hints +
+               hstate->num_hints[HINT_TYPE_SCAN_METHOD]);
+       hstate->leading_hint = (LeadingHint **) (hstate->join_hints +
+               hstate->num_hints[HINT_TYPE_JOIN_METHOD]);
+       hstate->set_hints = (SetHint **) (hstate->leading_hint +
+               hstate->num_hints[HINT_TYPE_LEADING]);
+       hstate->rows_hints = (RowsHint **) (hstate->set_hints +
+               hstate->num_hints[HINT_TYPE_SET]);
+       hstate->parallel_hints = (ParallelHint **) (hstate->rows_hints +
+               hstate->num_hints[HINT_TYPE_ROWS]);
+       hstate->memoize_hints = (JoinMethodHint **) (hstate->parallel_hints +
+               hstate->num_hints[HINT_TYPE_PARALLEL]);
 
        return hstate;
 }
@@ -1256,35 +2051,29 @@ ScanMethodHintParse(ScanMethodHint *hint, HintState *hstate, Query *parse,
        List               *name_list = NIL;
        int                             length;
 
-       if ((str = parse_parentheses(str, &name_list, hint->base.type)) == NULL)
+       if ((str = parse_parentheses(str, &name_list, hint_keyword)) == NULL)
                return NULL;
 
        /* Parse relation name and index name(s) if given hint accepts. */
        length = list_length(name_list);
-       if (length > 0)
-       {
-               hint->relname = linitial(name_list);
-               hint->indexnames = list_delete_first(name_list);
 
-               /* check whether the hint accepts index name(s). */
-               if (hint_keyword != HINT_KEYWORD_INDEXSCAN &&
-#if PG_VERSION_NUM >= 90200
-                       hint_keyword != HINT_KEYWORD_INDEXONLYSCAN &&
-#endif
-                       hint_keyword != HINT_KEYWORD_BITMAPSCAN &&
-                       length != 1)
-               {
-                       hint_ereport(str,
-                                                ("%s hint accepts only one relation.",
-                                                 hint->base.keyword));
-                       hint->base.state = HINT_STATE_ERROR;
-                       return str;
-               }
+       /* at least twp parameters required */
+       if (length < 1)
+       {
+               hint_ereport(str,
+                                        ("%s hint requires a relation.",  hint->base.keyword));
+               hint->base.state = HINT_STATE_ERROR;
+               return str;
        }
-       else
+
+       hint->relname = linitial(name_list);
+       hint->indexnames = list_delete_first(name_list);
+
+       /* check whether the hint accepts index name(s) */
+       if (length > 1 && !SCAN_HINT_ACCEPTS_INDEX_NAMES(hint_keyword))
        {
                hint_ereport(str,
-                                        ("%s hint requires a relation.",
+                                        ("%s hint accepts only one relation.",
                                          hint->base.keyword));
                hint->base.state = HINT_STATE_ERROR;
                return str;
@@ -1299,9 +2088,17 @@ ScanMethodHintParse(ScanMethodHint *hint, HintState *hstate, Query *parse,
                case HINT_KEYWORD_INDEXSCAN:
                        hint->enforce_mask = ENABLE_INDEXSCAN;
                        break;
+               case HINT_KEYWORD_INDEXSCANREGEXP:
+                       hint->enforce_mask = ENABLE_INDEXSCAN;
+                       hint->regexp = true;
+                       break;
                case HINT_KEYWORD_BITMAPSCAN:
                        hint->enforce_mask = ENABLE_BITMAPSCAN;
                        break;
+               case HINT_KEYWORD_BITMAPSCANREGEXP:
+                       hint->enforce_mask = ENABLE_BITMAPSCAN;
+                       hint->regexp = true;
+                       break;
                case HINT_KEYWORD_TIDSCAN:
                        hint->enforce_mask = ENABLE_TIDSCAN;
                        break;
@@ -1317,14 +2114,16 @@ ScanMethodHintParse(ScanMethodHint *hint, HintState *hstate, Query *parse,
                case HINT_KEYWORD_NOTIDSCAN:
                        hint->enforce_mask = ENABLE_ALL_SCAN ^ ENABLE_TIDSCAN;
                        break;
-#if PG_VERSION_NUM >= 90200
                case HINT_KEYWORD_INDEXONLYSCAN:
                        hint->enforce_mask = ENABLE_INDEXSCAN | ENABLE_INDEXONLYSCAN;
                        break;
+               case HINT_KEYWORD_INDEXONLYSCANREGEXP:
+                       hint->enforce_mask = ENABLE_INDEXSCAN | ENABLE_INDEXONLYSCAN;
+                       hint->regexp = true;
+                       break;
                case HINT_KEYWORD_NOINDEXONLYSCAN:
                        hint->enforce_mask = ENABLE_ALL_SCAN ^ ENABLE_INDEXONLYSCAN;
                        break;
-#endif
                default:
                        hint_ereport(str, ("Unrecognized hint keyword \"%s\".", keyword));
                        return NULL;
@@ -1342,7 +2141,7 @@ JoinMethodHintParse(JoinMethodHint *hint, HintState *hstate, Query *parse,
        HintKeyword             hint_keyword = hint->base.hint_keyword;
        List               *name_list = NIL;
 
-       if ((str = parse_parentheses(str, &name_list, hint->base.type)) == NULL)
+       if ((str = parse_parentheses(str, &name_list, hint_keyword)) == NULL)
                return NULL;
 
        hint->nrels = list_length(name_list);
@@ -1399,6 +2198,10 @@ JoinMethodHintParse(JoinMethodHint *hint, HintState *hstate, Query *parse,
                case HINT_KEYWORD_NOHASHJOIN:
                        hint->enforce_mask = ENABLE_ALL_JOIN ^ ENABLE_HASHJOIN;
                        break;
+               case HINT_KEYWORD_MEMOIZE:
+               case HINT_KEYWORD_NOMEMOIZE:
+                       /* nothing to do here */
+                       break;
                default:
                        hint_ereport(str, ("Unrecognized hint keyword \"%s\".", keyword));
                        return NULL;
@@ -1408,25 +2211,86 @@ JoinMethodHintParse(JoinMethodHint *hint, HintState *hstate, Query *parse,
        return str;
 }
 
+static bool
+OuterInnerPairCheck(OuterInnerRels *outer_inner)
+{
+       ListCell *l;
+       if (outer_inner->outer_inner_pair == NIL)
+       {
+               if (outer_inner->relation)
+                       return true;
+               else
+                       return false;
+       }
+
+       if (list_length(outer_inner->outer_inner_pair) == 2)
+       {
+               foreach(l, outer_inner->outer_inner_pair)
+               {
+                       if (!OuterInnerPairCheck(lfirst(l)))
+                               return false;
+               }
+       }
+       else
+               return false;
+
+       return true;
+}
+
+static List *
+OuterInnerList(OuterInnerRels *outer_inner)
+{
+       List               *outer_inner_list = NIL;
+       ListCell           *l;
+       OuterInnerRels *outer_inner_rels;
+
+       foreach(l, outer_inner->outer_inner_pair)
+       {
+               outer_inner_rels = (OuterInnerRels *)(lfirst(l));
+
+               if (outer_inner_rels->relation != NULL)
+                       outer_inner_list = lappend(outer_inner_list,
+                                                                          outer_inner_rels->relation);
+               else
+                       outer_inner_list = list_concat(outer_inner_list,
+                                                                                  OuterInnerList(outer_inner_rels));
+       }
+       return outer_inner_list;
+}
+
 static const char *
 LeadingHintParse(LeadingHint *hint, HintState *hstate, Query *parse,
                                 const char *str)
 {
-       List   *name_list = NIL;
+       List               *name_list = NIL;
+       OuterInnerRels *outer_inner = NULL;
 
-       if ((str = parse_parentheses(str, &name_list, hint->base.type)) == NULL)
+       if ((str = parse_parentheses_Leading(str, &name_list, &outer_inner)) ==
+               NULL)
                return NULL;
 
+       if (outer_inner != NULL)
+               name_list = OuterInnerList(outer_inner);
+
        hint->relations = name_list;
+       hint->outer_inner = outer_inner;
 
        /* A Leading hint requires at least two relations */
-       if (list_length(hint->relations) < 2)
+       if ( hint->outer_inner == NULL && list_length(hint->relations) < 2)
        {
                hint_ereport(hint->base.hint_str,
                                         ("%s hint requires at least two relations.",
                                          HINT_LEADING));
                hint->base.state = HINT_STATE_ERROR;
        }
+       else if (hint->outer_inner != NULL &&
+                        !OuterInnerPairCheck(hint->outer_inner))
+       {
+               hint_ereport(hint->base.hint_str,
+                                        ("%s hint requires two sets of relations when parentheses nests.",
+                                         HINT_LEADING));
+               hint->base.state = HINT_STATE_ERROR;
+       }
 
        return str;
 }
@@ -1436,7 +2300,8 @@ SetHintParse(SetHint *hint, HintState *hstate, Query *parse, const char *str)
 {
        List   *name_list = NIL;
 
-       if ((str = parse_parentheses(str, &name_list, hint->base.type)) == NULL)
+       if ((str = parse_parentheses(str, &name_list, hint->base.hint_keyword))
+               == NULL)
                return NULL;
 
        hint->words = name_list;
@@ -1458,107 +2323,407 @@ SetHintParse(SetHint *hint, HintState *hstate, Query *parse, const char *str)
        return str;
 }
 
-/*
- * set GUC parameter functions
- */
-
-static int
-set_config_option_wrapper(const char *name, const char *value,
-                                                 GucContext context, GucSource source,
-                                                 GucAction action, bool changeVal, int elevel)
+static const char *
+RowsHintParse(RowsHint *hint, HintState *hstate, Query *parse,
+                         const char *str)
 {
-       int                             result = 0;
-       MemoryContext   ccxt = CurrentMemoryContext;
-
-       PG_TRY();
-       {
-#if PG_VERSION_NUM >= 90200
-               result = set_config_option(name, value, context, source,
-                                                                  action, changeVal, 0);
-#else
-               result = set_config_option(name, value, context, source,
-                                                                  action, changeVal);
-#endif
-       }
-       PG_CATCH();
-       {
-               ErrorData          *errdata;
-
-               /* Save error info */
-               MemoryContextSwitchTo(ccxt);
-               errdata = CopyErrorData();
-               FlushErrorState();
+       HintKeyword             hint_keyword = hint->base.hint_keyword;
+       List               *name_list = NIL;
+       char               *rows_str;
+       char               *end_ptr;
+       ListCell   *l;
+       int                     i = 0;
 
-               ereport(elevel, (errcode(errdata->sqlerrcode),
-                               errmsg("%s", errdata->message),
-                               errdata->detail ? errdetail("%s", errdata->detail) : 0,
-                               errdata->hint ? errhint("%s", errdata->hint) : 0));
-               FreeErrorData(errdata);
-       }
-       PG_END_TRY();
+       if ((str = parse_parentheses(str, &name_list, hint_keyword)) == NULL)
+               return NULL;
 
-       return result;
-}
+       /* Last element must be rows specification */
+       hint->nrels = list_length(name_list) - 1;
 
-static int
-set_config_options(SetHint **options, int noptions, GucContext context)
-{
-       int     i;
-       int     save_nestlevel;
+       if (hint->nrels < 1)
+       {
+               hint_ereport(str,
+                                        ("%s hint needs at least one relation followed by one correction term.",
+                                         hint->base.keyword));
+               hint->base.state = HINT_STATE_ERROR;
 
-       save_nestlevel = NewGUCNestLevel();
+               return str;
+       }
+       
 
-       for (i = 0; i < noptions; i++)
+       /*
+        * Transform relation names from list to array to sort them with qsort
+        * after.
+        */
+       hint->relnames = palloc(sizeof(char *) * hint->nrels);
+       foreach (l, name_list)
        {
-               SetHint    *hint = options[i];
-               int                     result;
+               if (hint->nrels <= i)
+                       break;
+               hint->relnames[i] = lfirst(l);
+               i++;
+       }
+
+       /* Retieve rows estimation */
+       rows_str = list_nth(name_list, hint->nrels);
+       hint->rows_str = rows_str;              /* store as-is for error logging */
+       if (rows_str[0] == '#')
+       {
+               hint->value_type = RVT_ABSOLUTE;
+               rows_str++;
+       }
+       else if (rows_str[0] == '+')
+       {
+               hint->value_type = RVT_ADD;
+               rows_str++;
+       }
+       else if (rows_str[0] == '-')
+       {
+               hint->value_type = RVT_SUB;
+               rows_str++;
+       }
+       else if (rows_str[0] == '*')
+       {
+               hint->value_type = RVT_MULTI;
+               rows_str++;
+       }
+       else
+       {
+               hint_ereport(rows_str, ("Unrecognized rows value type notation."));
+               hint->base.state = HINT_STATE_ERROR;
+               return str;
+       }
+       hint->rows = strtod(rows_str, &end_ptr);
+       if (*end_ptr)
+       {
+               hint_ereport(rows_str,
+                                        ("%s hint requires valid number as rows estimation.",
+                                         hint->base.keyword));
+               hint->base.state = HINT_STATE_ERROR;
+               return str;
+       }
+
+       /* A join hint requires at least two relations */
+       if (hint->nrels < 2)
+       {
+               hint_ereport(str,
+                                        ("%s hint requires at least two relations.",
+                                         hint->base.keyword));
+               hint->base.state = HINT_STATE_ERROR;
+               return str;
+       }
+
+       list_free(name_list);
+
+       /* Sort relnames in alphabetical order. */
+       qsort(hint->relnames, hint->nrels, sizeof(char *), RelnameCmp);
+
+       return str;
+}
+
+static const char *
+ParallelHintParse(ParallelHint *hint, HintState *hstate, Query *parse,
+                                 const char *str)
+{
+       HintKeyword             hint_keyword = hint->base.hint_keyword;
+       List               *name_list = NIL;
+       int                             length;
+       char   *end_ptr;
+       int             nworkers;
+       bool    force_parallel = false;
+
+       if ((str = parse_parentheses(str, &name_list, hint_keyword)) == NULL)
+               return NULL;
+
+       /* Parse relation name and index name(s) if given hint accepts. */
+       length = list_length(name_list);
+
+       if (length < 2 || length > 3)
+       {
+               hint_ereport(")",
+                                        ("wrong number of arguments (%d): %s",
+                                         length,  hint->base.keyword));
+               hint->base.state = HINT_STATE_ERROR;
+               return str;
+       }
+
+       hint->relname = linitial(name_list);
+               
+       /* The second parameter is number of workers */
+       hint->nworkers_str = list_nth(name_list, 1);
+       nworkers = strtod(hint->nworkers_str, &end_ptr);
+       if (*end_ptr || nworkers < 0 || nworkers > max_worker_processes)
+       {
+               if (*end_ptr)
+                       hint_ereport(hint->nworkers_str,
+                                                ("number of workers must be a number: %s",
+                                                 hint->base.keyword));
+               else if (nworkers < 0)
+                       hint_ereport(hint->nworkers_str,
+                                                ("number of workers must be greater than zero: %s",
+                                                 hint->base.keyword));
+               else if (nworkers > max_worker_processes)
+                       hint_ereport(hint->nworkers_str,
+                                                ("number of workers = %d is larger than max_worker_processes(%d): %s",
+                                                 nworkers, max_worker_processes, hint->base.keyword));
+
+               hint->base.state = HINT_STATE_ERROR;
+       }
+
+       hint->nworkers = nworkers;
+
+       /* optional third parameter is specified */
+       if (length == 3)
+       {
+               const char *modeparam = (const char *)list_nth(name_list, 2);
+               if (pg_strcasecmp(modeparam, "hard") == 0)
+                       force_parallel = true;
+               else if (pg_strcasecmp(modeparam, "soft") != 0)
+               {
+                       hint_ereport(modeparam,
+                                                ("enforcement must be soft or hard: %s",
+                                                        hint->base.keyword));
+                       hint->base.state = HINT_STATE_ERROR;
+               }
+       }
+
+       hint->force_parallel = force_parallel;
+
+       if (hint->base.state != HINT_STATE_ERROR &&
+               nworkers > max_hint_nworkers)
+               max_hint_nworkers = nworkers;
+
+       return str;
+}
+
+/*
+ * set GUC parameter functions
+ */
+
+static int
+get_current_scan_mask()
+{
+       int mask = 0;
+
+       if (enable_seqscan)
+               mask |= ENABLE_SEQSCAN;
+       if (enable_indexscan)
+               mask |= ENABLE_INDEXSCAN;
+       if (enable_bitmapscan)
+               mask |= ENABLE_BITMAPSCAN;
+       if (enable_tidscan)
+               mask |= ENABLE_TIDSCAN;
+       if (enable_indexonlyscan)
+               mask |= ENABLE_INDEXONLYSCAN;
+
+       return mask;
+}
+
+static int
+get_current_join_mask()
+{
+       int mask = 0;
+
+       if (enable_nestloop)
+               mask |= ENABLE_NESTLOOP;
+       if (enable_mergejoin)
+               mask |= ENABLE_MERGEJOIN;
+       if (enable_hashjoin)
+               mask |= ENABLE_HASHJOIN;
+       if (enable_memoize)
+               mask |= ENABLE_MEMOIZE;
+
+       return mask;
+}
+
+/*
+ * Sets GUC prameters without throwing exception. Reutrns false if something
+ * wrong.
+ */
+static int
+set_config_option_noerror(const char *name, const char *value,
+                                                 GucContext context, GucSource source,
+                                                 GucAction action, bool changeVal, int elevel)
+{
+       int                             result = 0;
+       MemoryContext   ccxt = CurrentMemoryContext;
+
+       PG_TRY();
+       {
+               result = set_config_option(name, value, context, source,
+                                                                  action, changeVal, 0, false);
+       }
+       PG_CATCH();
+       {
+               ErrorData          *errdata;
+
+               /* Save error info */
+               MemoryContextSwitchTo(ccxt);
+               errdata = CopyErrorData();
+               FlushErrorState();
+
+               ereport(elevel,
+                               (errcode(errdata->sqlerrcode),
+                                errmsg("%s", errdata->message),
+                                errdata->detail ? errdetail("%s", errdata->detail) : 0,
+                                errdata->hint ? errhint("%s", errdata->hint) : 0));
+               msgqno = qno;
+               FreeErrorData(errdata);
+       }
+       PG_END_TRY();
+
+       return result;
+}
+
+/*
+ * Sets GUC parameter of int32 type without throwing exceptions. Returns false
+ * if something wrong.
+ */
+static int
+set_config_int32_option(const char *name, int32 value, GucContext context)
+{
+       char buf[16];   /* enough for int32 */
+
+       if (snprintf(buf, 16, "%d", value) < 0)
+       {
+               ereport(pg_hint_plan_parse_message_level,
+                               (errmsg ("Failed to convert integer to string: %d", value)));
+               return false;
+       }
+
+       return
+               set_config_option_noerror(name, buf, context,
+                                                                 PGC_S_SESSION, GUC_ACTION_SAVE, true,
+                                                                 pg_hint_plan_parse_message_level);
+}
+
+/*
+ * Sets GUC parameter of double type without throwing exceptions. Returns false
+ * if something wrong.
+ */
+static int
+set_config_double_option(const char *name, double value, GucContext context)
+{
+       char *buf = float8out_internal(value);
+       int       result;
+
+       result = set_config_option_noerror(name, buf, context,
+                                                                          PGC_S_SESSION, GUC_ACTION_SAVE, true,
+                                                                          pg_hint_plan_parse_message_level);
+       pfree(buf);
+       return result;
+}
+
+/* setup scan method enforcement according to given options */
+static void
+setup_guc_enforcement(SetHint **options, int noptions, GucContext context)
+{
+       int     i;
+
+       for (i = 0; i < noptions; i++)
+       {
+               SetHint    *hint = options[i];
+               int                     result;
 
                if (!hint_state_enabled(hint))
                        continue;
 
-               result = set_config_option_wrapper(hint->name, hint->value, context,
+               result = set_config_option_noerror(hint->name, hint->value, context,
                                                                                   PGC_S_SESSION, GUC_ACTION_SAVE, true,
-                                                                                  pg_hint_plan_parse_messages);
+                                                                                  pg_hint_plan_parse_message_level);
                if (result != 0)
                        hint->base.state = HINT_STATE_USED;
                else
                        hint->base.state = HINT_STATE_ERROR;
        }
 
-       return save_nestlevel;
+       return;
+}
+
+/*
+ * Setup parallel execution environment.
+ *
+ * If hint is not NULL, set up using it, elsewise reset to initial environment.
+ */
+static void
+setup_parallel_plan_enforcement(ParallelHint *hint, HintState *state)
+{
+       if (hint)
+       {
+               hint->base.state = HINT_STATE_USED;
+               set_config_int32_option("max_parallel_workers_per_gather",
+                                                               hint->nworkers, state->context);
+       }
+       else
+               set_config_int32_option("max_parallel_workers_per_gather",
+                                                               state->init_nworkers, state->context);
+
+       /* force means that enforce parallel as far as possible */
+       if (hint && hint->force_parallel && hint->nworkers > 0)
+       {
+               set_config_double_option("parallel_tuple_cost", 0.0, state->context);
+               set_config_double_option("parallel_setup_cost", 0.0, state->context);
+               set_config_int32_option("min_parallel_table_scan_size", 0,
+                                                               state->context);
+               set_config_int32_option("min_parallel_index_scan_size", 0,
+                                                               state->context);
+       }
+       else
+       {
+               set_config_double_option("parallel_tuple_cost",
+                                                               state->init_paratup_cost, state->context);
+               set_config_double_option("parallel_setup_cost",
+                                                               state->init_parasetup_cost, state->context);
+               set_config_int32_option("min_parallel_table_scan_size",
+                                                               state->init_min_para_tablescan_size,
+                                                               state->context);
+               set_config_int32_option("min_parallel_index_scan_size",
+                                                               state->init_min_para_indexscan_size,
+                                                               state->context);
+       }
 }
 
 #define SET_CONFIG_OPTION(name, type_bits) \
-       set_config_option_wrapper((name), \
+       set_config_option_noerror((name), \
                (mask & (type_bits)) ? "true" : "false", \
                context, PGC_S_SESSION, GUC_ACTION_SAVE, true, ERROR)
 
+
+/*
+ * Setup GUC environment to enforce scan methods. If scanhint is NULL, reset
+ * GUCs to the saved state in state.
+ */
 static void
-set_scan_config_options(unsigned char enforce_mask, GucContext context)
+setup_scan_method_enforcement(ScanMethodHint *scanhint, HintState *state)
 {
+       unsigned char   enforce_mask = state->init_scan_mask;
+       GucContext              context = state->context;
        unsigned char   mask;
 
+       if (scanhint)
+       {
+               enforce_mask = scanhint->enforce_mask;
+               scanhint->base.state = HINT_STATE_USED;
+       }
+
        if (enforce_mask == ENABLE_SEQSCAN || enforce_mask == ENABLE_INDEXSCAN ||
                enforce_mask == ENABLE_BITMAPSCAN || enforce_mask == ENABLE_TIDSCAN
-#if PG_VERSION_NUM >= 90200
                || enforce_mask == (ENABLE_INDEXSCAN | ENABLE_INDEXONLYSCAN)
-#endif
                )
                mask = enforce_mask;
        else
-               mask = enforce_mask & current_hint->init_scan_mask;
+               mask = enforce_mask & current_hint_state->init_scan_mask;
 
        SET_CONFIG_OPTION("enable_seqscan", ENABLE_SEQSCAN);
        SET_CONFIG_OPTION("enable_indexscan", ENABLE_INDEXSCAN);
        SET_CONFIG_OPTION("enable_bitmapscan", ENABLE_BITMAPSCAN);
        SET_CONFIG_OPTION("enable_tidscan", ENABLE_TIDSCAN);
-#if PG_VERSION_NUM >= 90200
        SET_CONFIG_OPTION("enable_indexonlyscan", ENABLE_INDEXONLYSCAN);
-#endif
 }
 
 static void
-set_join_config_options(unsigned char enforce_mask, GucContext context)
+set_join_config_options(unsigned char enforce_mask, bool set_memoize,
+                                               GucContext context)
 {
        unsigned char   mask;
 
@@ -1566,117 +2731,39 @@ set_join_config_options(unsigned char enforce_mask, GucContext context)
                enforce_mask == ENABLE_HASHJOIN)
                mask = enforce_mask;
        else
-               mask = enforce_mask & current_hint->init_join_mask;
+               mask = enforce_mask & current_hint_state->init_join_mask;
 
        SET_CONFIG_OPTION("enable_nestloop", ENABLE_NESTLOOP);
        SET_CONFIG_OPTION("enable_mergejoin", ENABLE_MERGEJOIN);
        SET_CONFIG_OPTION("enable_hashjoin", ENABLE_HASHJOIN);
-}
 
-/*
- * pg_hint_plan hook functions
- */
-
-static void
-pg_hint_plan_ProcessUtility(Node *parsetree, const char *queryString,
-                                                       ParamListInfo params, bool isTopLevel,
-                                                       DestReceiver *dest, char *completionTag)
-{
-       Node                               *node;
-
-       if (!pg_hint_plan_enable_hint)
-       {
-               if (prev_ProcessUtility)
-                       (*prev_ProcessUtility) (parsetree, queryString, params,
-                                                                       isTopLevel, dest, completionTag);
-               else
-                       standard_ProcessUtility(parsetree, queryString, params,
-                                                                       isTopLevel, dest, completionTag);
-
-               return;
-       }
-
-       node = parsetree;
-       if (IsA(node, ExplainStmt))
-       {
-               /*
-                * Draw out parse tree of actual query from Query struct of EXPLAIN
-                * statement.
-                */
-               ExplainStmt        *stmt;
-               Query              *query;
-
-               stmt = (ExplainStmt *) node;
-
-               Assert(IsA(stmt->query, Query));
-               query = (Query *) stmt->query;
-
-               if (query->commandType == CMD_UTILITY && query->utilityStmt != NULL)
-                       node = query->utilityStmt;
-       }
+       if (set_memoize)
+               SET_CONFIG_OPTION("enable_memoize", ENABLE_MEMOIZE);
 
        /*
-        * If the query was a EXECUTE or CREATE TABLE AS EXECUTE, get query string
-        * specified to preceding PREPARE command to use it as source of hints.
+        * Hash join may be rejected for the reason of estimated memory usage. Try
+        * getting rid of that limitation.
         */
-       if (IsA(node, ExecuteStmt))
+       if (enforce_mask == ENABLE_HASHJOIN)
        {
-               ExecuteStmt        *stmt;
+               char                    buf[32];
+               int                             new_multipler;
 
-               stmt = (ExecuteStmt *) node;
-               stmt_name = stmt->name;
-       }
-#if PG_VERSION_NUM >= 90200
-       /*
-        * CREATE AS EXECUTE behavior has changed since 9.2, so we must handle it
-        * specially here.
-        */
-       if (IsA(node, CreateTableAsStmt))
-       {
-               CreateTableAsStmt          *stmt;
-               Query              *query;
+               /* See final_cost_hashjoin(). */
+               new_multipler = MAX_KILOBYTES / work_mem;
 
-               stmt = (CreateTableAsStmt *) node;
-               Assert(IsA(stmt->query, Query));
-               query = (Query *) stmt->query;
+               /* See guc.c for the upper limit */
+               if (new_multipler >= 1000)
+                       new_multipler = 1000;
 
-               if (query->commandType == CMD_UTILITY &&
-                       IsA(query->utilityStmt, ExecuteStmt))
+               if (new_multipler > hash_mem_multiplier)
                {
-                       ExecuteStmt *estmt = (ExecuteStmt *) query->utilityStmt;
-                       stmt_name = estmt->name;
+                       snprintf(buf, sizeof(buf), UINT64_FORMAT, (uint64)new_multipler);
+                       set_config_option_noerror("hash_mem_multiplier", buf,
+                                                                         context, PGC_S_SESSION, GUC_ACTION_SAVE,
+                                                                         true, ERROR);
                }
        }
-#endif
-       if (stmt_name)
-       {
-               PG_TRY();
-               {
-                       if (prev_ProcessUtility)
-                               (*prev_ProcessUtility) (parsetree, queryString, params,
-                                                                               isTopLevel, dest, completionTag);
-                       else
-                               standard_ProcessUtility(parsetree, queryString, params,
-                                                                               isTopLevel, dest, completionTag);
-               }
-               PG_CATCH();
-               {
-                       stmt_name = NULL;
-                       PG_RE_THROW();
-               }
-               PG_END_TRY();
-
-               stmt_name = NULL;
-
-               return;
-       }
-
-       if (prev_ProcessUtility)
-               (*prev_ProcessUtility) (parsetree, queryString, params,
-                                                               isTopLevel, dest, completionTag);
-       else
-               standard_ProcessUtility(parsetree, queryString, params,
-                                                               isTopLevel, dest, completionTag);
 }
 
 /*
@@ -1690,7 +2777,7 @@ push_hint(HintState *hstate)
        HintStateStack = lcons(hstate, HintStateStack);
 
        /* Pushed hint is the one which should be used hereafter. */
-       current_hint = hstate;
+       current_hint_state = hstate;
 }
 
 /* Pop a hint from hint stack.  Popped hint is automatically discarded. */
@@ -1702,111 +2789,365 @@ pop_hint(void)
                elog(ERROR, "hint stack is empty");
 
        /*
-        * Take a hint at the head from the list, and free it.  Switch current_hint
-        * to point new head (NULL if the list is empty).
+        * Take a hint at the head from the list, and free it.  Switch
+        * current_hint_state to point new head (NULL if the list is empty).
         */
        HintStateStack = list_delete_first(HintStateStack);
-       HintStateDelete(current_hint);
+       HintStateDelete(current_hint_state);
        if(HintStateStack == NIL)
-               current_hint = NULL;
+               current_hint_state = NULL;
        else
-               current_hint = (HintState *) lfirst(list_head(HintStateStack));
+               current_hint_state = (HintState *) lfirst(list_head(HintStateStack));
+}
+
+/*
+ * Retrieve and store hint string from given query or from the hint table.
+ */
+static void
+get_current_hint_string(Query *query, const char *query_str,
+                                               JumbleState *jstate)
+{
+       MemoryContext   oldcontext;
+
+       /* We shouldn't get here for internal queries. */
+       Assert (hint_inhibit_level == 0);
+
+       /* We shouldn't get here if hint is disabled. */
+       Assert (pg_hint_plan_enable_hint);
+
+       /* Do not anything if we have already tried to get hints for this query. */
+       if (current_hint_retrieved)
+               return;
+
+       /* No way to retrieve hints from empty string. */
+       if (!query_str)
+               return;
+
+       /* Don't parse the current query hereafter */
+       current_hint_retrieved = true;
+
+       /* Make sure trashing old hint string */
+       if (current_hint_str)
+       {
+               pfree((void *)current_hint_str);
+               current_hint_str = NULL;
+       }
+
+       /* increment the query number */
+       qnostr[0] = 0;
+       if (debug_level > 1)
+               snprintf(qnostr, sizeof(qnostr), "[qno=0x%x]", qno++);
+       qno++;
+
+       /* search the hint table for a hint if requested */
+       if (pg_hint_plan_enable_hint_table)
+       {
+               int                     query_len;
+               char       *normalized_query;
+
+               if (!IsQueryIdEnabled())
+               {
+                       /*
+                        * compute_query_id was turned off while enable_hint_table is
+                        * on. Do not go ahead and complain once until it is turned on
+                        * again.
+                        */
+                       if (!hint_table_deactivated)
+                               ereport(WARNING,
+                                               (errmsg ("hint table feature is deactivated because queryid is not available"),
+                                                errhint("Set compute_query_id to \"auto\" or \"on\" to use hint table.")));
+
+                       hint_table_deactivated = true;
+                       return;
+               }
+
+               if (hint_table_deactivated)
+               {
+                       ereport(LOG, (errmsg ("hint table feature is reactivated")));
+                       hint_table_deactivated = false;
+               }
+
+               if (!jstate)
+                       jstate = JumbleQuery(query, query_str);
+
+               if (!jstate)
+                       return;
+
+               /*
+                * Normalize the query string by replacing constants with '?'
+                */
+               /*
+                * Search hint string which is stored keyed by query string
+                * and application name.  The query string is normalized to allow
+                * fuzzy matching.
+                *
+                * Adding 1 byte to query_len ensures that the returned string has
+                * a terminating NULL.
+                */
+               query_len = strlen(query_str) + 1;
+               normalized_query =
+                       generate_normalized_query(jstate, query_str, 0, &query_len);
+
+               /*
+                * find a hint for the normalized query. the result should be in
+                * TopMemoryContext
+                */
+               oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+               current_hint_str =
+                       get_hints_from_table(normalized_query, application_name);
+               MemoryContextSwitchTo(oldcontext);
+
+               if (debug_level > 1)
+               {
+                       if (current_hint_str)
+                               ereport(pg_hint_plan_debug_message_level,
+                                               (errmsg("pg_hint_plan[qno=0x%x]: "
+                                                               "hints from table: \"%s\": "
+                                                               "normalized_query=\"%s\", "
+                                                               "application name =\"%s\"",
+                                                               qno, current_hint_str,
+                                                               normalized_query, application_name),
+                                                errhidestmt(msgqno != qno),
+                                                errhidecontext(msgqno != qno)));
+                       else
+                               ereport(pg_hint_plan_debug_message_level,
+                                               (errmsg("pg_hint_plan[qno=0x%x]: "
+                                                               "no match found in table:  "
+                                                               "application name = \"%s\", "
+                                                               "normalized_query=\"%s\"",
+                                                               qno, application_name,
+                                                               normalized_query),
+                                                errhidestmt(msgqno != qno),
+                                                errhidecontext(msgqno != qno)));
+                       
+                       msgqno = qno;
+               }
+
+               /* retrun if we have hint string here */
+               if (current_hint_str)
+                       return;
+       }
+
+       /* get hints from the comment */
+       oldcontext = MemoryContextSwitchTo(TopMemoryContext);
+       current_hint_str = get_hints_from_comment(query_str);
+       MemoryContextSwitchTo(oldcontext);
+
+       if (debug_level > 1)
+       {
+               if (debug_level == 2 && query_str && debug_query_string &&
+                       strcmp(query_str, debug_query_string))
+                       ereport(pg_hint_plan_debug_message_level,
+                                       (errmsg("hints in comment=\"%s\"",
+                                                       current_hint_str ? current_hint_str : "(none)"),
+                                        errhidestmt(msgqno != qno),
+                                        errhidecontext(msgqno != qno)));
+               else
+                       ereport(pg_hint_plan_debug_message_level,
+                                       (errmsg("hints in comment=\"%s\", query=\"%s\", debug_query_string=\"%s\"",
+                                                       current_hint_str ? current_hint_str : "(none)",
+                                                       query_str ? query_str : "(none)",
+                                                       debug_query_string ? debug_query_string : "(none)"),
+                                        errhidestmt(msgqno != qno),
+                                        errhidecontext(msgqno != qno)));
+               msgqno = qno;
+       }
+}
+
+/*
+ * Retrieve hint string from the current query.
+ */
+static void
+pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query,
+                                                               JumbleState *jstate)
+{
+       if (prev_post_parse_analyze_hook)
+               prev_post_parse_analyze_hook(pstate, query, jstate);
+
+       if (!pg_hint_plan_enable_hint || hint_inhibit_level > 0)
+               return;
+
+       /* always retrieve hint from the top-level query string */
+       if (plpgsql_recurse_level == 0)
+               current_hint_retrieved = false;
+
+       /*
+        * Jumble state is required when hint table is used.  This is the only
+        * chance to have one already generated in-core.  If it's not the case, no
+        * use to do the work now and pg_hint_plan_planner() will do the all work.
+        */
+       if (jstate)
+               get_current_hint_string(query, pstate->p_sourcetext, jstate);
 }
 
+/*
+ * Read and set up hint information
+ */
 static PlannedStmt *
-pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
+pg_hint_plan_planner(Query *parse, const char *query_string, int cursorOptions, ParamListInfo boundParams)
 {
        int                             save_nestlevel;
        PlannedStmt        *result;
        HintState          *hstate;
+       const char         *prev_hint_str = NULL;
 
        /*
-        * Use standard planner if pg_hint_plan is disabled.  Other hook functions
-        * try to change plan with current_hint if any, so set it to NULL.
+        * Use standard planner if pg_hint_plan is disabled or current nesting 
+        * depth is nesting depth of SPI calls. Other hook functions try to change
+        * plan with current_hint_state if any, so set it to NULL.
         */
-       if (!pg_hint_plan_enable_hint)
+       if (!pg_hint_plan_enable_hint || hint_inhibit_level > 0)
        {
-               current_hint = NULL;
-
-               if (prev_planner)
-                       return (*prev_planner) (parse, cursorOptions, boundParams);
-               else
-                       return standard_planner(parse, cursorOptions, boundParams);
+               if (debug_level > 1)
+                       ereport(pg_hint_plan_debug_message_level,
+                                       (errmsg ("pg_hint_plan%s: planner: enable_hint=%d,"
+                                                        " hint_inhibit_level=%d",
+                                                        qnostr, pg_hint_plan_enable_hint,
+                                                        hint_inhibit_level),
+                                        errhidestmt(msgqno != qno)));
+               msgqno = qno;
+
+               goto standard_planner_proc;
        }
 
-       /* Create hint struct from parse tree. */
-       hstate = parse_head_comment(parse);
-
        /*
-        * Use standard planner if the statement has not valid hint.  Other hook
-        * functions try to change plan with current_hint if any, so set it to
-        * NULL.
+        * SQL commands invoked in plpgsql functions may also have hints. In that
+        * case override the upper level hint by the new hint.
         */
-       if (!hstate)
+       if (plpgsql_recurse_level > 0)
        {
-               current_hint = NULL;
+               const char       *tmp_hint_str = current_hint_str;
 
-               if (prev_planner)
-                       return (*prev_planner) (parse, cursorOptions, boundParams);
-               else
-                       return standard_planner(parse, cursorOptions, boundParams);
+               /* don't let get_current_hint_string free this string */
+               current_hint_str = NULL;
+
+               current_hint_retrieved = false;
+
+               get_current_hint_string(parse, query_string, NULL);
+
+               if (current_hint_str == NULL)
+                       current_hint_str = tmp_hint_str;
+               else if (tmp_hint_str != NULL)
+                       pfree((void *)tmp_hint_str);
        }
+       else
+               get_current_hint_string(parse, query_string, NULL);
+
+       /* No hints, go the normal way */
+       if (!current_hint_str)
+               goto standard_planner_proc;
+
+       /* parse the hint into hint state struct */
+       hstate = create_hintstate(parse, pstrdup(current_hint_str));
 
+       /* run standard planner if we're given with no valid hints */
+       if (!hstate)
+       {
+               /* forget invalid hint string */
+               if (current_hint_str)
+               {
+                       pfree((void *)current_hint_str);
+                       current_hint_str = NULL;
+               }
+               
+               goto standard_planner_proc;
+       }
+       
        /*
         * Push new hint struct to the hint stack to disable previous hint context.
         */
        push_hint(hstate);
 
-       /* Set GUC parameters which are specified with Set hint. */
-       save_nestlevel = set_config_options(current_hint->set_hints,
-                                                                               current_hint->num_hints[HINT_TYPE_SET],
-                                                                               current_hint->context);
+       /*  Set scan enforcement here. */
+       save_nestlevel = NewGUCNestLevel();
 
-       if (enable_seqscan)
-               current_hint->init_scan_mask |= ENABLE_SEQSCAN;
-       if (enable_indexscan)
-               current_hint->init_scan_mask |= ENABLE_INDEXSCAN;
-       if (enable_bitmapscan)
-               current_hint->init_scan_mask |= ENABLE_BITMAPSCAN;
-       if (enable_tidscan)
-               current_hint->init_scan_mask |= ENABLE_TIDSCAN;
-#if PG_VERSION_NUM >= 90200
-       if (enable_indexonlyscan)
-               current_hint->init_scan_mask |= ENABLE_INDEXONLYSCAN;
-#endif
-       if (enable_nestloop)
-               current_hint->init_join_mask |= ENABLE_NESTLOOP;
-       if (enable_mergejoin)
-               current_hint->init_join_mask |= ENABLE_MERGEJOIN;
-       if (enable_hashjoin)
-               current_hint->init_join_mask |= ENABLE_HASHJOIN;
+       /* Apply Set hints, then save it as the initial state  */
+       setup_guc_enforcement(current_hint_state->set_hints,
+                                                  current_hint_state->num_hints[HINT_TYPE_SET],
+                                                  current_hint_state->context);
+       
+       current_hint_state->init_scan_mask = get_current_scan_mask();
+       current_hint_state->init_join_mask = get_current_join_mask();
+       current_hint_state->init_min_para_tablescan_size =
+               min_parallel_table_scan_size;
+       current_hint_state->init_min_para_indexscan_size =
+               min_parallel_index_scan_size;
+       current_hint_state->init_paratup_cost = parallel_tuple_cost;
+       current_hint_state->init_parasetup_cost = parallel_setup_cost;
 
        /*
-        * Use PG_TRY mechanism to recover GUC parameters and current_hint to the
-        * state when this planner started when error occurred in planner.
+        * max_parallel_workers_per_gather should be non-zero here if Workers hint
+        * is specified.
+        */
+       if (max_hint_nworkers > 0 && max_parallel_workers_per_gather < 1)
+               set_config_int32_option("max_parallel_workers_per_gather",
+                                                               1, current_hint_state->context);
+       current_hint_state->init_nworkers = max_parallel_workers_per_gather;
+
+       if (debug_level > 1)
+       {
+               ereport(pg_hint_plan_debug_message_level,
+                               (errhidestmt(msgqno != qno),
+                                errmsg("pg_hint_plan%s: planner", qnostr))); 
+               msgqno = qno;
+       }
+
+       /*
+        * The planner call below may replace current_hint_str. Store and restore
+        * it so that the subsequent planning in the upper level doesn't get
+        * confused.
+        */
+       recurse_level++;
+       prev_hint_str = current_hint_str;
+       current_hint_str = NULL;
+       
+       /*
+        * Use PG_TRY mechanism to recover GUC parameters and current_hint_state to
+        * the state when this planner started when error occurred in planner.
         */
        PG_TRY();
        {
                if (prev_planner)
-                       result = (*prev_planner) (parse, cursorOptions, boundParams);
+                       result = (*prev_planner) (parse, query_string,
+                                                                         cursorOptions, boundParams);
                else
-                       result = standard_planner(parse, cursorOptions, boundParams);
+                       result = standard_planner(parse, query_string,
+                                                                         cursorOptions, boundParams);
+
+               current_hint_str = prev_hint_str;
+               recurse_level--;
        }
        PG_CATCH();
        {
                /*
                 * Rollback changes of GUC parameters, and pop current hint context
-                * from hint stack to rewind the state.
+                * from hint stack to rewind the state. current_hint_str will be freed
+                * by context deletion.
                 */
+               current_hint_str = prev_hint_str;
+               recurse_level--;
                AtEOXact_GUC(true, save_nestlevel);
                pop_hint();
                PG_RE_THROW();
        }
        PG_END_TRY();
 
+
+       /*
+        * current_hint_str is useless after planning of the top-level query.
+        * There's a case where the caller has multiple queries. This causes hint
+        * parsing multiple times for the same string but we don't have a simple
+        * and reliable way to distinguish that case from the case where of
+        * separate queries.
+        */
+       if (recurse_level < 1)
+               current_hint_retrieved = false;
+
        /* Print hint in debug mode. */
-       if (pg_hint_plan_debug_print)
-               HintStateDump(current_hint);
+       if (debug_level == 1)
+               HintStateDump(current_hint_state);
+       else if (debug_level > 1)
+               HintStateDump2(current_hint_state);
 
        /*
         * Rollback changes of GUC parameters, and pop current hint context from
@@ -1816,54 +3157,213 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
        pop_hint();
 
        return result;
+
+standard_planner_proc:
+       if (debug_level > 1)
+       {
+               ereport(pg_hint_plan_debug_message_level,
+                               (errhidestmt(msgqno != qno),
+                                errmsg("pg_hint_plan%s: planner: no valid hint",
+                                               qnostr)));
+               msgqno = qno;
+       }
+       current_hint_state = NULL;
+       if (prev_planner)
+               result =  (*prev_planner) (parse, query_string,
+                                                                  cursorOptions, boundParams);
+       else
+               result = standard_planner(parse, query_string,
+                                                                 cursorOptions, boundParams);
+
+       /* The upper-level planner still needs the current hint state */
+       if (HintStateStack != NIL)
+               current_hint_state = (HintState *) lfirst(list_head(HintStateStack));
+
+       return result;
 }
 
 /*
- * Return scan method hint which matches given aliasname.
+ * Find scan method hint to be applied to the given relation
+ *
  */
 static ScanMethodHint *
-find_scan_hint(PlannerInfo *root, RelOptInfo *rel)
+find_scan_hint(PlannerInfo *root, Index relid)
+{
+       RelOptInfo         *rel;
+       RangeTblEntry  *rte;
+       ScanMethodHint  *real_name_hint = NULL;
+       ScanMethodHint  *alias_hint = NULL;
+       int                             i;
+
+       /* This should not be a join rel */
+       Assert(relid > 0);
+       rel = root->simple_rel_array[relid];
+
+       /*
+        * This function is called for any RelOptInfo or its inheritance parent if
+        * any. If we are called from inheritance planner, the RelOptInfo for the
+        * parent of target child relation is not set in the planner info.
+        *
+        * Otherwise we should check that the reloptinfo is base relation or
+        * inheritance children.
+        */
+       if (rel &&
+               rel->reloptkind != RELOPT_BASEREL &&
+               rel->reloptkind != RELOPT_OTHER_MEMBER_REL)
+               return NULL;
+
+       /*
+        * This is baserel or appendrel children. We can refer to RangeTblEntry.
+        */
+       rte = root->simple_rte_array[relid];
+       Assert(rte);
+
+       /* We don't hint on other than relation and foreign tables */
+       if (rte->rtekind != RTE_RELATION ||
+               rte->relkind == RELKIND_FOREIGN_TABLE)
+               return NULL;
+
+       /* Find scan method hint, which matches given names, from the list. */
+       for (i = 0; i < current_hint_state->num_hints[HINT_TYPE_SCAN_METHOD]; i++)
+       {
+               ScanMethodHint *hint = current_hint_state->scan_hints[i];
+
+               /* We ignore disabled hints. */
+               if (!hint_state_enabled(hint))
+                       continue;
+
+               if (!alias_hint &&
+                       RelnameCmp(&rte->eref->aliasname, &hint->relname) == 0)
+                       alias_hint = hint;
+
+               /* check the real name for appendrel children */
+               if (!real_name_hint &&
+                       rel && rel->reloptkind == RELOPT_OTHER_MEMBER_REL)
+               {
+                       char *realname = get_rel_name(rte->relid);
+
+                       if (realname && RelnameCmp(&realname, &hint->relname) == 0)
+                               real_name_hint = hint;
+               }
+
+               /* No more match expected, break  */
+               if(alias_hint && real_name_hint)
+                       break;
+       }
+
+       /* real name match precedes alias match */
+       if (real_name_hint)
+               return real_name_hint;
+
+       return alias_hint;
+}
+
+static ParallelHint *
+find_parallel_hint(PlannerInfo *root, Index relid)
 {
+       RelOptInfo         *rel;
        RangeTblEntry  *rte;
+       ParallelHint    *real_name_hint = NULL;
+       ParallelHint    *alias_hint = NULL;
        int                             i;
 
+       /* This should not be a join rel */
+       Assert(relid > 0);
+       rel = root->simple_rel_array[relid];
+
        /*
-        * We can't apply scan method hint if the relation is:
-        *   - not a base relation
-        *   - not an ordinary relation (such as join and subquery)
+        * Parallel planning is appliable only on base relation, which has
+        * RelOptInfo. 
         */
-       if (rel->reloptkind != RELOPT_BASEREL || rel->rtekind != RTE_RELATION)
+       if (!rel)
                return NULL;
 
-       rte = root->simple_rte_array[rel->relid];
-
-       /* We can't force scan method of foreign tables */
-       if (rte->relkind == RELKIND_FOREIGN_TABLE)
+       /*
+        * We have set root->glob->parallelModeOK if needed. What we should do here
+        * is just following the decision of planner.
+        */
+       if (!rel->consider_parallel)
                return NULL;
 
-       /* Find scan method hint, which matches given names, from the list. */
-       for (i = 0; i < current_hint->num_hints[HINT_TYPE_SCAN_METHOD]; i++)
+       /*
+        * This is baserel or appendrel children. We can refer to RangeTblEntry.
+        */
+       rte = root->simple_rte_array[relid];
+       Assert(rte);
+
+       /* Find parallel method hint, which matches given names, from the list. */
+       for (i = 0; i < current_hint_state->num_hints[HINT_TYPE_PARALLEL]; i++)
        {
-               ScanMethodHint *hint = current_hint->scan_hints[i];
+               ParallelHint *hint = current_hint_state->parallel_hints[i];
 
                /* We ignore disabled hints. */
                if (!hint_state_enabled(hint))
                        continue;
 
-               if (RelnameCmp(&rte->eref->aliasname, &hint->relname) == 0)
-                       return hint;
+               if (!alias_hint &&
+                       RelnameCmp(&rte->eref->aliasname, &hint->relname) == 0)
+                       alias_hint = hint;
+
+               /* check the real name for appendrel children */
+               if (!real_name_hint &&
+                       rel && rel->reloptkind == RELOPT_OTHER_MEMBER_REL)
+               {
+                       char *realname = get_rel_name(rte->relid);
+
+                       if (realname && RelnameCmp(&realname, &hint->relname) == 0)
+                               real_name_hint = hint;
+               }
+
+               /* No more match expected, break  */
+               if(alias_hint && real_name_hint)
+                       break;
        }
 
-       return NULL;
+       /* real name match precedes alias match */
+       if (real_name_hint)
+               return real_name_hint;
+
+       return alias_hint;
+}
+
+/*
+ * regexeq
+ *
+ * Returns TRUE on match, FALSE on no match.
+ *
+ *   s1 --- the data to match against
+ *   s2 --- the pattern
+ *
+ * Because we copy s1 to NameData, make the size of s1 less than NAMEDATALEN.
+ */
+static bool
+regexpeq(const char *s1, const char *s2)
+{
+       NameData        name;
+       text       *regexp;
+       Datum           result;
+
+       strcpy(name.data, s1);
+       regexp = cstring_to_text(s2);
+
+       result = DirectFunctionCall2Coll(nameregexeq,
+                                                                        DEFAULT_COLLATION_OID,
+                                                                        NameGetDatum(&name),
+                                                                        PointerGetDatum(regexp));
+       return DatumGetBool(result);
 }
 
+
+/* Remove indexes instructed not to use by hint. */
 static void
-delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
+restrict_indexes(PlannerInfo *root, ScanMethodHint *hint, RelOptInfo *rel,
+                          bool using_parent_hint)
 {
        ListCell           *cell;
-       ListCell           *prev;
        ListCell           *next;
        StringInfoData  buf;
+       RangeTblEntry  *rte = root->simple_rte_array[rel->relid];
+       Oid                             relationObjectId = rte->relid;
 
        /*
         * We delete all the IndexOptInfo list and prevent you from being usable by
@@ -1889,8 +3389,7 @@ delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
         * Leaving only an specified index, we delete it from a IndexOptInfo list
         * other than it.
         */
-       prev = NULL;
-       if (pg_hint_plan_debug_print)
+       if (debug_level > 0)
                initStringInfo(&buf);
 
        for (cell = list_head(rel->indexlist); cell; cell = next)
@@ -1900,17 +3399,169 @@ delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
                ListCell           *l;
                bool                    use_index = false;
 
-               next = lnext(cell);
-
+               next = lnext(rel->indexlist, cell);
                foreach(l, hint->indexnames)
                {
-                       if (RelnameCmp(&indexname, &lfirst(l)) == 0)
+                       char   *hintname = (char *) lfirst(l);
+                       bool    result;
+
+                       if (hint->regexp)
+                               result = regexpeq(indexname, hintname);
+                       else
+                               result = RelnameCmp(&indexname, &hintname) == 0;
+
+                       if (result)
+                       {
+                               use_index = true;
+                               if (debug_level > 0)
+                               {
+                                       appendStringInfoCharMacro(&buf, ' ');
+                                       quote_value(&buf, indexname);
+                               }
+
+                               break;
+                       }
+               }
+
+               /*
+                * Apply index restriction of parent hint to children. Since index
+                * inheritance is not explicitly described we should search for an
+                * children's index with the same definition to that of the parent.
+                */
+               if (using_parent_hint && !use_index)
+               {
+                       foreach(l, current_hint_state->parent_index_infos)
                        {
+                               int                                     i;
+                               HeapTuple                       ht_idx;
+                               ParentIndexInfo    *p_info = (ParentIndexInfo *)lfirst(l);
+
+                               /*
+                                * we check the 'same' index by comparing uniqueness, access
+                                * method and index key columns.
+                                */
+                               if (p_info->indisunique != info->unique ||
+                                       p_info->method != info->relam ||
+                                       list_length(p_info->column_names) != info->ncolumns)
+                                       continue;
+
+                               /* Check if index key columns match */
+                               for (i = 0; i < info->ncolumns; i++)
+                               {
+                                       char       *c_attname = NULL;
+                                       char       *p_attname = NULL;
+
+                                       p_attname = list_nth(p_info->column_names, i);
+
+                                       /*
+                                        * if both of the key of the same position are expressions,
+                                        * ignore them for now and check later.
+                                        */
+                                       if (info->indexkeys[i] == 0 && !p_attname)
+                                               continue;
+
+                                       /* deny if one is expression while another is not */
+                                       if (info->indexkeys[i] == 0 || !p_attname)
+                                               break;
+
+                                       c_attname = get_attname(relationObjectId,
+                                                                                       info->indexkeys[i], false);
+
+                                       /* deny if any of column attributes don't match */
+                                       if (strcmp(p_attname, c_attname) != 0 ||
+                                               p_info->indcollation[i] != info->indexcollations[i] ||
+                                               p_info->opclass[i] != info->opcintype[i]||
+                                               ((p_info->indoption[i] & INDOPTION_DESC) != 0)
+                                               != info->reverse_sort[i] ||
+                                               ((p_info->indoption[i] & INDOPTION_NULLS_FIRST) != 0)
+                                               != info->nulls_first[i])
+                                               break;
+                               }
+
+                               /* deny this if any difference found */
+                               if (i != info->ncolumns)
+                                       continue;
+
+                               /* check on key expressions  */
+                               if ((p_info->expression_str && (info->indexprs != NIL)) ||
+                                       (p_info->indpred_str && (info->indpred != NIL)))
+                               {
+                                       /* fetch the index of this child */
+                                       ht_idx = SearchSysCache1(INDEXRELID,
+                                                                                        ObjectIdGetDatum(info->indexoid));
+
+                                       /* check expressions if both expressions are available */
+                                       if (p_info->expression_str &&
+                                               !heap_attisnull(ht_idx, Anum_pg_index_indexprs, NULL))
+                                       {
+                                               Datum       exprsDatum;
+                                               bool        isnull;
+                                               Datum       result;
+
+                                               /*
+                                                * to change the expression's parameter of child's
+                                                * index to strings
+                                                */
+                                               exprsDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
+                                                                                                        Anum_pg_index_indexprs,
+                                                                                                        &isnull);
+
+                                               result = DirectFunctionCall2(pg_get_expr,
+                                                                                                        exprsDatum,
+                                                                                                        ObjectIdGetDatum(
+                                                                                                                relationObjectId));
+
+                                               /* deny if expressions don't match */
+                                               if (strcmp(p_info->expression_str,
+                                                                  text_to_cstring(DatumGetTextP(result))) != 0)
+                                               {
+                                                       /* Clean up */
+                                                       ReleaseSysCache(ht_idx);
+                                                       continue;
+                                               }
+                                       }
+
+                                       /* compare index predicates  */
+                                       if (p_info->indpred_str &&
+                                               !heap_attisnull(ht_idx, Anum_pg_index_indpred, NULL))
+                                       {
+                                               Datum       predDatum;
+                                               bool        isnull;
+                                               Datum       result;
+
+                                               predDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
+                                                                                                        Anum_pg_index_indpred,
+                                                                                                        &isnull);
+
+                                               result = DirectFunctionCall2(pg_get_expr,
+                                                                                                        predDatum,
+                                                                                                        ObjectIdGetDatum(
+                                                                                                                relationObjectId));
+
+                                               if (strcmp(p_info->indpred_str,
+                                                                  text_to_cstring(DatumGetTextP(result))) != 0)
+                                               {
+                                                       /* Clean up */
+                                                       ReleaseSysCache(ht_idx);
+                                                       continue;
+                                               }
+                                       }
+
+                                       /* Clean up */
+                                       ReleaseSysCache(ht_idx);
+                               }
+                               else if (p_info->expression_str || (info->indexprs != NIL))
+                                       continue;
+                               else if (p_info->indpred_str || (info->indpred != NIL))
+                                       continue;
+
                                use_index = true;
-                               if (pg_hint_plan_debug_print)
+
+                               /* to log the candidate of index */
+                               if (debug_level > 0)
                                {
                                        appendStringInfoCharMacro(&buf, ' ');
-                                       dump_quote_value(&buf, indexname);
+                                       quote_value(&buf, indexname);
                                }
 
                                break;
@@ -1918,27 +3569,40 @@ delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
                }
 
                if (!use_index)
-                       rel->indexlist = list_delete_cell(rel->indexlist, cell, prev);
-               else
-                       prev = cell;
+               {
+                       rel->indexlist = list_delete_cell(rel->indexlist, cell);
 
+                       /*
+                        * The cells after the deleted cell have been moved towards the
+                        * list head by 1 element.  the next iteration should visit the
+                        * cell at the same address if any.
+                        */
+                       if (next)
+                               next = cell;
+               }
+                       
                pfree(indexname);
        }
 
-       if (pg_hint_plan_debug_print)
+       if (debug_level > 0)
        {
-               char   *relname;
                StringInfoData  rel_buf;
+               char *disprelname = "";
 
-               if (OidIsValid(relationObjectId))
-                       relname = get_rel_name(relationObjectId);
+               /*
+                * If this hint targetted the parent, use the real name of this
+                * child. Otherwise use hint specification.
+                */
+               if (using_parent_hint)
+                       disprelname = get_rel_name(rte->relid);
                else
-                       relname = hint->relname;
+                       disprelname = hint->relname;
+                       
 
                initStringInfo(&rel_buf);
-               dump_quote_value(&rel_buf, relname);
+               quote_value(&rel_buf, disprelname);
 
-               ereport(LOG,
+               ereport(pg_hint_plan_debug_message_level,
                                (errmsg("available indexes for %s(%s):%s",
                                         hint->base.keyword,
                                         rel_buf.data,
@@ -1948,70 +3612,305 @@ delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
        }
 }
 
-static void
-pg_hint_plan_get_relation_info(PlannerInfo *root, Oid relationObjectId,
-                                                          bool inhparent, RelOptInfo *rel)
+/* 
+ * Return information of index definition.
+ */
+static ParentIndexInfo *
+get_parent_index_info(Oid indexoid, Oid relid)
 {
-       ScanMethodHint *hint;
+       ParentIndexInfo *p_info = palloc(sizeof(ParentIndexInfo));
+       Relation            indexRelation;
+       Form_pg_index   index;
+       char               *attname;
+       int                             i;
 
-       if (prev_get_relation_info)
-               (*prev_get_relation_info) (root, relationObjectId, inhparent, rel);
+       indexRelation = index_open(indexoid, RowExclusiveLock);
 
-       /* Do nothing if we don't have valid hint in this context. */
-       if (!current_hint)
-               return;
+       index = indexRelation->rd_index;
+
+       p_info->indisunique = index->indisunique;
+       p_info->method = indexRelation->rd_rel->relam;
+
+       p_info->column_names = NIL;
+       p_info->indcollation = (Oid *) palloc(sizeof(Oid) * index->indnatts);
+       p_info->opclass = (Oid *) palloc(sizeof(Oid) * index->indnatts);
+       p_info->indoption = (int16 *) palloc(sizeof(Oid) * index->indnatts);
+
+       /*
+        * Collect relation attribute names of index columns for index
+        * identification, not index attribute names. NULL means expression index
+        * columns.
+        */
+       for (i = 0; i < index->indnatts; i++)
+       {
+               attname = get_attname(relid, index->indkey.values[i], true);
+               p_info->column_names = lappend(p_info->column_names, attname);
+
+               p_info->indcollation[i] = indexRelation->rd_indcollation[i];
+               p_info->opclass[i] = indexRelation->rd_opcintype[i];
+               p_info->indoption[i] = indexRelation->rd_indoption[i];
+       }
+
+       /*
+        * to check to match the expression's parameter of index with child indexes
+        */
+       p_info->expression_str = NULL;
+       if(!heap_attisnull(indexRelation->rd_indextuple, Anum_pg_index_indexprs,
+                                          NULL))
+       {
+               Datum       exprsDatum;
+               bool            isnull;
+               Datum           result;
+
+               exprsDatum = SysCacheGetAttr(INDEXRELID, indexRelation->rd_indextuple,
+                                                                        Anum_pg_index_indexprs, &isnull);
+
+               result = DirectFunctionCall2(pg_get_expr,
+                                                                        exprsDatum,
+                                                                        ObjectIdGetDatum(relid));
+
+               p_info->expression_str = text_to_cstring(DatumGetTextP(result));
+       }
+
+       /*
+        * to check to match the predicate's parameter of index with child indexes
+        */
+       p_info->indpred_str = NULL;
+       if(!heap_attisnull(indexRelation->rd_indextuple, Anum_pg_index_indpred,
+                                          NULL))
+       {
+               Datum       predDatum;
+               bool            isnull;
+               Datum           result;
+
+               predDatum = SysCacheGetAttr(INDEXRELID, indexRelation->rd_indextuple,
+                                                                        Anum_pg_index_indpred, &isnull);
+
+               result = DirectFunctionCall2(pg_get_expr,
+                                                                        predDatum,
+                                                                        ObjectIdGetDatum(relid));
+
+               p_info->indpred_str = text_to_cstring(DatumGetTextP(result));
+       }
+
+       index_close(indexRelation, NoLock);
+
+       return p_info;
+}
+
+/*
+ * cancel hint enforcement
+ */
+static void
+reset_hint_enforcement()
+{
+       setup_scan_method_enforcement(NULL, current_hint_state);
+       setup_parallel_plan_enforcement(NULL, current_hint_state);
+}
+
+/*
+ * Set planner guc parameters according to corresponding scan hints.  Returns
+ * bitmap of HintTypeBitmap. If shint or phint is not NULL, set used hint
+ * there respectively.
+ */
+static int
+setup_hint_enforcement(PlannerInfo *root, RelOptInfo *rel,
+                                          ScanMethodHint **rshint, ParallelHint **rphint)
+{
+       Index   new_parent_relid = 0;
+       ListCell *l;
+       ScanMethodHint *shint = NULL;
+       ParallelHint   *phint = NULL;
+       bool                    inhparent = root->simple_rte_array[rel->relid]->inh;
+       Oid             relationObjectId = root->simple_rte_array[rel->relid]->relid;
+       int                             ret = 0;
+
+       /* reset returns if requested  */
+       if (rshint != NULL) *rshint = NULL;
+       if (rphint != NULL) *rphint = NULL;
 
+       /*
+        * We could register the parent relation of the following children here
+        * when inhparent == true but inheritnce planner doesn't call this function
+        * for parents. Since we cannot distinguish who called this function we
+        * cannot do other than always seeking the parent regardless of who called
+        * this function.
+        */
        if (inhparent)
        {
-               /* store does relids of parent table. */
-               current_hint->parent_relid = rel->relid;
+               /* set up only parallel hints for parent relation */
+               phint = find_parallel_hint(root, rel->relid);
+               if (phint)
+               {
+                       setup_parallel_plan_enforcement(phint, current_hint_state);
+                       if (rphint) *rphint = phint;
+                       ret |= HINT_BM_PARALLEL;
+                       return ret;
+               }
+
+               if (debug_level > 1)
+                       ereport(pg_hint_plan_debug_message_level,
+                                       (errhidestmt(true),
+                                        errmsg ("pg_hint_plan%s: setup_hint_enforcement"
+                                                        " skipping inh parent: relation=%u(%s), inhparent=%d,"
+                                                        " current_hint_state=%p, hint_inhibit_level=%d",
+                                                        qnostr, relationObjectId,
+                                                        get_rel_name(relationObjectId),
+                                                        inhparent, current_hint_state, hint_inhibit_level)));
+               return 0;
+       }
+
+       if (bms_num_members(rel->top_parent_relids) == 1)
+       {
+               new_parent_relid = bms_next_member(rel->top_parent_relids, -1);
+               current_hint_state->current_root = root;
+               Assert(new_parent_relid > 0);
+       }
+       else
+       {
+               /* This relation doesn't have a parent. Cancel current_hint_state. */
+               current_hint_state->parent_relid = 0;
+               current_hint_state->parent_scan_hint = NULL;
+               current_hint_state->parent_parallel_hint = NULL;
        }
-       else if (current_hint->parent_relid != 0)
+
+       if (new_parent_relid > 0)
        {
                /*
-                * We use the same GUC parameter if this table is the child table of a
-                * table called pg_hint_plan_get_relation_info just before that.
+                * Here we found a new parent for the current relation. Scan continues
+                * hint to other childrens of this parent so remember it to avoid
+                * redundant setup cost.
                 */
-               ListCell   *l;
+               current_hint_state->parent_relid = new_parent_relid;
+                               
+               /* Find hints for the parent */
+               current_hint_state->parent_scan_hint =
+                       find_scan_hint(root, current_hint_state->parent_relid);
+
+               current_hint_state->parent_parallel_hint =
+                       find_parallel_hint(root, current_hint_state->parent_relid);
 
-               /* append_rel_list contains all append rels; ignore others */
-               foreach(l, root->append_rel_list)
+               /*
+                * If hint is found for the parent, apply it for this child instead
+                * of its own.
+                */
+               if (current_hint_state->parent_scan_hint)
                {
-                       AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
+                       ScanMethodHint * pshint = current_hint_state->parent_scan_hint;
 
-                       /* This rel is child table. */
-                       if (appinfo->parent_relid == current_hint->parent_relid &&
-                               appinfo->child_relid == rel->relid)
+                       pshint->base.state = HINT_STATE_USED;
+
+                       /* Apply index mask in the same manner to the parent. */
+                       if (pshint->indexnames)
                        {
-                               if (current_hint->parent_hint)
-                                       delete_indexes(current_hint->parent_hint, rel,
-                                                                  relationObjectId);
+                               Oid                     parentrel_oid;
+                               Relation        parent_rel;
 
-                               return;
+                               parentrel_oid =
+                                       root->simple_rte_array[current_hint_state->parent_relid]->relid;
+                               parent_rel = table_open(parentrel_oid, NoLock);
+
+                               /* Search the parent relation for indexes match the hint spec */
+                               foreach(l, RelationGetIndexList(parent_rel))
+                               {
+                                       Oid         indexoid = lfirst_oid(l);
+                                       char       *indexname = get_rel_name(indexoid);
+                                       ListCell   *lc;
+                                       ParentIndexInfo *parent_index_info;
+
+                                       foreach(lc, pshint->indexnames)
+                                       {
+                                               if (RelnameCmp(&indexname, &lfirst(lc)) == 0)
+                                                       break;
+                                       }
+                                       if (!lc)
+                                               continue;
+
+                                       parent_index_info =
+                                               get_parent_index_info(indexoid, parentrel_oid);
+                                       current_hint_state->parent_index_infos =
+                                               lappend(current_hint_state->parent_index_infos,
+                                                               parent_index_info);
+                               }
+                               table_close(parent_rel, NoLock);
                        }
                }
+       }
 
-               /* This rel is not inherit table. */
-               current_hint->parent_relid = 0;
-               current_hint->parent_hint = NULL;
+       shint = find_scan_hint(root, rel->relid);
+       if (!shint)
+               shint = current_hint_state->parent_scan_hint;
+
+       if (shint)
+       {
+               bool using_parent_hint =
+                       (shint == current_hint_state->parent_scan_hint);
+
+               ret |= HINT_BM_SCAN_METHOD;
+
+               /* Setup scan enforcement environment */
+               setup_scan_method_enforcement(shint, current_hint_state);
+
+               /* restrict unwanted inexes */
+               restrict_indexes(root, shint, rel, using_parent_hint);
+
+               if (debug_level > 1)
+               {
+                       char *additional_message = "";
+
+                       if (shint == current_hint_state->parent_scan_hint)
+                               additional_message = " by parent hint";
+
+                       ereport(pg_hint_plan_debug_message_level,
+                                       (errhidestmt(true),
+                                        errmsg ("pg_hint_plan%s: setup_hint_enforcement"
+                                                        " index deletion%s:"
+                                                        " relation=%u(%s), inhparent=%d, "
+                                                        "current_hint_state=%p,"
+                                                        " hint_inhibit_level=%d, scanmask=0x%x",
+                                                        qnostr, additional_message,
+                                                        relationObjectId,
+                                                        get_rel_name(relationObjectId),
+                                                        inhparent, current_hint_state,
+                                                        hint_inhibit_level,
+                                                        shint->enforce_mask)));
+               }
        }
 
-       /*
-        * If scan method hint was given, reset GUC parameters which control
-        * planner behavior about choosing scan methods.
-        */
-       if ((hint = find_scan_hint(root, rel)) == NULL)
+       /* Do the same for parallel plan enforcement */
+       phint = find_parallel_hint(root, rel->relid);
+       if (!phint)
+               phint = current_hint_state->parent_parallel_hint;
+
+       setup_parallel_plan_enforcement(phint, current_hint_state);
+
+       if (phint)
+               ret |= HINT_BM_PARALLEL;
+
+       /* Nothing to apply. Reset the scan mask to intial state */
+       if (!shint && ! phint)
        {
-               set_scan_config_options(current_hint->init_scan_mask,
-                                                               current_hint->context);
-               return;
+               if (debug_level > 1)
+                       ereport(pg_hint_plan_debug_message_level,
+                                       (errhidestmt (true),
+                                        errmsg ("pg_hint_plan%s: setup_hint_enforcement"
+                                                        " no hint applied:"
+                                                        " relation=%u(%s), inhparent=%d, current_hint=%p,"
+                                                        " hint_inhibit_level=%d, scanmask=0x%x",
+                                                        qnostr, relationObjectId,
+                                                        get_rel_name(relationObjectId),
+                                                        inhparent, current_hint_state, hint_inhibit_level,
+                                                        current_hint_state->init_scan_mask)));
+
+               setup_scan_method_enforcement(NULL,     current_hint_state);
+
+               return ret;
        }
-       set_scan_config_options(hint->enforce_mask, current_hint->context);
-       hint->base.state = HINT_STATE_USED;
-       if (inhparent)
-               current_hint->parent_hint = hint;
-       else
-               delete_indexes(hint, rel, InvalidOid);
+
+       if (rshint != NULL) *rshint = shint;
+       if (rphint != NULL) *rphint = phint;
+
+       return ret;
 }
 
 /*
@@ -2081,7 +3980,30 @@ find_join_hint(Relids joinrelids)
        List       *join_hint;
        ListCell   *l;
 
-       join_hint = current_hint->join_hint_level[bms_num_members(joinrelids)];
+       join_hint = current_hint_state->join_hint_level[bms_num_members(joinrelids)];
+
+       foreach(l, join_hint)
+       {
+               JoinMethodHint *hint = (JoinMethodHint *) lfirst(l);
+
+               if (bms_equal(joinrelids, hint->joinrelids))
+                       return hint;
+       }
+
+       return NULL;
+}
+
+
+/*
+ * Return memoize hint which matches given joinrelids.
+ */
+static JoinMethodHint *
+find_memoize_hint(Relids joinrelids)
+{
+       List       *join_hint;
+       ListCell   *l;
+
+       join_hint = current_hint_state->memoize_hint_level[bms_num_members(joinrelids)];
 
        foreach(l, join_hint)
        {
@@ -2094,6 +4016,121 @@ find_join_hint(Relids joinrelids)
        return NULL;
 }
 
+
+static Relids
+OuterInnerJoinCreate(OuterInnerRels *outer_inner, LeadingHint *leading_hint,
+       PlannerInfo *root, List *initial_rels, HintState *hstate, int nbaserel)
+{
+       OuterInnerRels *outer_rels;
+       OuterInnerRels *inner_rels;
+       Relids                  outer_relids;
+       Relids                  inner_relids;
+       Relids                  join_relids;
+       JoinMethodHint *hint;
+
+       if (outer_inner->relation != NULL)
+       {
+               return bms_make_singleton(
+                                       find_relid_aliasname(root, outer_inner->relation,
+                                                                                initial_rels,
+                                                                                leading_hint->base.hint_str));
+       }
+
+       outer_rels = linitial(outer_inner->outer_inner_pair);
+       inner_rels = llast(outer_inner->outer_inner_pair);
+
+       outer_relids = OuterInnerJoinCreate(outer_rels,
+                                                                               leading_hint,
+                                                                               root,
+                                                                               initial_rels,
+                                                                               hstate,
+                                                                               nbaserel);
+       inner_relids = OuterInnerJoinCreate(inner_rels,
+                                                                               leading_hint,
+                                                                               root,
+                                                                               initial_rels,
+                                                                               hstate,
+                                                                               nbaserel);
+
+       join_relids = bms_add_members(outer_relids, inner_relids);
+
+       if (bms_num_members(join_relids) > nbaserel)
+               return join_relids;
+
+       /*
+        * If we don't have join method hint, create new one for the
+        * join combination with all join methods are enabled.
+        */
+       hint = find_join_hint(join_relids);
+       if (hint == NULL)
+       {
+               /*
+                * Here relnames is not set, since Relids bitmap is sufficient to
+                * control paths of this query afterward.
+                */
+               hint = (JoinMethodHint *) JoinMethodHintCreate(
+                                       leading_hint->base.hint_str,
+                                       HINT_LEADING,
+                                       HINT_KEYWORD_LEADING);
+               hint->base.state = HINT_STATE_USED;
+               hint->nrels = bms_num_members(join_relids);
+               hint->enforce_mask = ENABLE_ALL_JOIN;
+               hint->joinrelids = bms_copy(join_relids);
+               hint->inner_nrels = bms_num_members(inner_relids);
+               hint->inner_joinrelids = bms_copy(inner_relids);
+
+               hstate->join_hint_level[hint->nrels] =
+                       lappend(hstate->join_hint_level[hint->nrels], hint);
+       }
+       else
+       {
+               hint->inner_nrels = bms_num_members(inner_relids);
+               hint->inner_joinrelids = bms_copy(inner_relids);
+       }
+
+       return join_relids;
+}
+
+static Relids
+create_bms_of_relids(Hint *base, PlannerInfo *root, List *initial_rels,
+               int nrels, char **relnames)
+{
+       int             relid;
+       Relids  relids = NULL;
+       int             j;
+       char   *relname;
+
+       for (j = 0; j < nrels; j++)
+       {
+               relname = relnames[j];
+
+               relid = find_relid_aliasname(root, relname, initial_rels,
+                                                                        base->hint_str);
+
+               if (relid == -1)
+                       base->state = HINT_STATE_ERROR;
+
+               /*
+                * the aliasname is not found(relid == 0) or same aliasname was used
+                * multiple times in a query(relid == -1)
+                */
+               if (relid <= 0)
+               {
+                       relids = NULL;
+                       break;
+               }
+               if (bms_is_member(relid, relids))
+               {
+                       hint_ereport(base->hint_str,
+                                                ("Relation name \"%s\" is duplicated.", relname));
+                       base->state = HINT_STATE_ERROR;
+                       break;
+               }
+
+               relids = bms_add_member(relids, relid);
+       }
+       return relids;
+}
 /*
  * Transform join method hint into handy form.
  *
@@ -2102,71 +4139,129 @@ find_join_hint(Relids joinrelids)
  *   - add join method hints which are necessary to enforce join order
  *     specified by Leading hint
  */
-static void
+static bool
 transform_join_hints(HintState *hstate, PlannerInfo *root, int nbaserel,
                List *initial_rels, JoinMethodHint **join_method_hints)
 {
        int                             i;
        int                             relid;
-       LeadingHint        *lhint;
        Relids                  joinrelids;
        int                             njoinrels;
        ListCell           *l;
+       char               *relname;
+       LeadingHint        *lhint = NULL;
+
+       /*
+        * Create bitmap of relids from alias names for each join method hint.
+        * Bitmaps are more handy than strings in join searching.
+        */
+       for (i = 0; i < hstate->num_hints[HINT_TYPE_JOIN_METHOD]; i++)
+       {
+               JoinMethodHint *hint = hstate->join_hints[i];
+
+               if (!hint_state_enabled(hint) || hint->nrels > nbaserel)
+                       continue;
+
+               hint->joinrelids = create_bms_of_relids(&(hint->base), root,
+                                                                        initial_rels, hint->nrels, hint->relnames);
+
+               if (hint->joinrelids == NULL || hint->base.state == HINT_STATE_ERROR)
+                       continue;
+
+               hstate->join_hint_level[hint->nrels] =
+                       lappend(hstate->join_hint_level[hint->nrels], hint);
+       }
+
+       /* ditto for memoize hints */
+       for (i = 0; i < hstate->num_hints[HINT_TYPE_MEMOIZE]; i++)
+       {
+               JoinMethodHint *hint = hstate->join_hints[i];
+
+               if (!hint_state_enabled(hint) || hint->nrels > nbaserel)
+                       continue;
+
+               hint->joinrelids = create_bms_of_relids(&(hint->base), root,
+                                                                        initial_rels, hint->nrels, hint->relnames);
+
+               if (hint->joinrelids == NULL || hint->base.state == HINT_STATE_ERROR)
+                       continue;
+
+               hstate->memoize_hint_level[hint->nrels] =
+                       lappend(hstate->memoize_hint_level[hint->nrels], hint);
+       }
+
+       /*
+        * Create bitmap of relids from alias names for each rows hint.
+        * Bitmaps are more handy than strings in join searching.
+        */
+       for (i = 0; i < hstate->num_hints[HINT_TYPE_ROWS]; i++)
+       {
+               RowsHint *hint = hstate->rows_hints[i];
+
+               if (!hint_state_enabled(hint) || hint->nrels > nbaserel)
+                       continue;
+
+               hint->joinrelids = create_bms_of_relids(&(hint->base), root,
+                                                                        initial_rels, hint->nrels, hint->relnames);
+       }
+
+       /* Do nothing if no Leading hint was supplied. */
+       if (hstate->num_hints[HINT_TYPE_LEADING] == 0)
+               return false;
 
        /*
-        * Create bitmap of relids from alias names for each join method hint.
-        * Bitmaps are more handy than strings in join searching.
-        */
-       for (i = 0; i < hstate->num_hints[HINT_TYPE_JOIN_METHOD]; i++)
+        * Decide whether to use Leading hint
+        */
+       for (i = 0; i < hstate->num_hints[HINT_TYPE_LEADING]; i++)
        {
-               JoinMethodHint *hint = hstate->join_hints[i];
-               int     j;
+               LeadingHint        *leading_hint = (LeadingHint *)hstate->leading_hint[i];
+               Relids                  relids;
 
-               if (!hint_state_enabled(hint) || hint->nrels > nbaserel)
+               if (leading_hint->base.state == HINT_STATE_ERROR)
                        continue;
 
-               bms_free(hint->joinrelids);
-               hint->joinrelids = NULL;
                relid = 0;
-               for (j = 0; j < hint->nrels; j++)
+               relids = NULL;
+
+               foreach(l, leading_hint->relations)
                {
-                       char   *relname = hint->relnames[j];
+                       relname = (char *)lfirst(l);;
 
                        relid = find_relid_aliasname(root, relname, initial_rels,
-                                                                                hint->base.hint_str);
-
+                                                                                leading_hint->base.hint_str);
                        if (relid == -1)
-                               hint->base.state = HINT_STATE_ERROR;
+                               leading_hint->base.state = HINT_STATE_ERROR;
 
                        if (relid <= 0)
                                break;
 
-                       if (bms_is_member(relid, hint->joinrelids))
+                       if (bms_is_member(relid, relids))
                        {
-                               hint_ereport(hint->base.hint_str,
+                               hint_ereport(leading_hint->base.hint_str,
                                                         ("Relation name \"%s\" is duplicated.", relname));
-                               hint->base.state = HINT_STATE_ERROR;
+                               leading_hint->base.state = HINT_STATE_ERROR;
                                break;
                        }
 
-                       hint->joinrelids = bms_add_member(hint->joinrelids, relid);
+                       relids = bms_add_member(relids, relid);
                }
 
-               if (relid <= 0 || hint->base.state == HINT_STATE_ERROR)
+               if (relid <= 0 || leading_hint->base.state == HINT_STATE_ERROR)
                        continue;
 
-               hstate->join_hint_level[hint->nrels] =
-                       lappend(hstate->join_hint_level[hint->nrels], hint);
+               if (lhint != NULL)
+               {
+                       hint_ereport(lhint->base.hint_str,
+                                ("Conflict %s hint.", HintTypeName[lhint->base.type]));
+                       lhint->base.state = HINT_STATE_DUPLICATION;
+               }
+               leading_hint->base.state = HINT_STATE_USED;
+               lhint = leading_hint;
        }
 
-       /* Do nothing if no Leading hint was supplied. */
-       if (hstate->num_hints[HINT_TYPE_LEADING] == 0)
-               return;
-
-       /* Do nothing if Leading hint is invalid. */
-       lhint = hstate->leading_hint;
-       if (!hint_state_enabled(lhint))
-               return;
+       /* check to exist Leading hint marked with 'used'. */
+       if (lhint == NULL)
+               return false;
 
        /*
         * We need join method hints which fit specified join order in every join
@@ -2181,209 +4276,268 @@ transform_join_hints(HintState *hstate, PlannerInfo *root, int nbaserel,
         */
        joinrelids = NULL;
        njoinrels = 0;
-       foreach(l, lhint->relations)
+       if (lhint->outer_inner == NULL)
        {
-               char   *relname = (char *)lfirst(l);
-               JoinMethodHint *hint;
-
-               /*
-                * Find relid of the relation which has given name.  If we have the
-                * name given in Leading hint multiple times in the join, nothing to
-                * do.
-                */
-               relid = find_relid_aliasname(root, relname, initial_rels,
-                                                                        hstate->hint_str);
-               if (relid == -1)
+               foreach(l, lhint->relations)
                {
-                       bms_free(joinrelids);
-                       return;
-               }
-               if (relid == 0)
-                       continue;
+                       JoinMethodHint *hint;
 
-               /* Found relid must not be in joinrelids. */
-               if (bms_is_member(relid, joinrelids))
-               {
-                       hint_ereport(lhint->base.hint_str,
-                                                ("Relation name \"%s\" is duplicated.", relname));
-                       lhint->base.state = HINT_STATE_ERROR;
-                       bms_free(joinrelids);
-                       return;
-               }
+                       relname = (char *)lfirst(l);
 
-               /* Create bitmap of relids for current join level. */
-               joinrelids = bms_add_member(joinrelids, relid);
-               njoinrels++;
+                       /*
+                        * Find relid of the relation which has given name.  If we have the
+                        * name given in Leading hint multiple times in the join, nothing to
+                        * do.
+                        */
+                       relid = find_relid_aliasname(root, relname, initial_rels,
+                                                                                hstate->hint_str);
 
-               /* We never have join method hint for single relation. */
-               if (njoinrels < 2)
-                       continue;
+                       /* Create bitmap of relids for current join level. */
+                       joinrelids = bms_add_member(joinrelids, relid);
+                       njoinrels++;
+
+                       /* We never have join method hint for single relation. */
+                       if (njoinrels < 2)
+                               continue;
 
-               /*
-                * If we don't have join method hint, create new one for the
-                * join combination with all join methods are enabled.
-                */
-               hint = find_join_hint(joinrelids);
-               if (hint == NULL)
-               {
                        /*
-                        * Here relnames is not set, since Relids bitmap is sufficient to
-                        * control paths of this query afterward.
+                        * If we don't have join method hint, create new one for the
+                        * join combination with all join methods are enabled.
                         */
-                       hint = (JoinMethodHint *) JoinMethodHintCreate(lhint->base.hint_str,
-                                                                                                                  HINT_LEADING,
-                                                                                                                 HINT_KEYWORD_LEADING);
-                       hint->base.state = HINT_STATE_USED;
-                       hint->nrels = njoinrels;
-                       hint->enforce_mask = ENABLE_ALL_JOIN;
-                       hint->joinrelids = bms_copy(joinrelids);
+                       hint = find_join_hint(joinrelids);
+                       if (hint == NULL)
+                       {
+                               /*
+                                * Here relnames is not set, since Relids bitmap is sufficient
+                                * to control paths of this query afterward.
+                                */
+                               hint = (JoinMethodHint *) JoinMethodHintCreate(
+                                                                                       lhint->base.hint_str,
+                                                                                       HINT_LEADING,
+                                                                                       HINT_KEYWORD_LEADING);
+                               hint->base.state = HINT_STATE_USED;
+                               hint->nrels = njoinrels;
+                               hint->enforce_mask = ENABLE_ALL_JOIN;
+                               hint->joinrelids = bms_copy(joinrelids);
+                       }
+
+                       join_method_hints[njoinrels] = hint;
+
+                       if (njoinrels >= nbaserel)
+                               break;
                }
+               bms_free(joinrelids);
 
-               join_method_hints[njoinrels] = hint;
+               if (njoinrels < 2)
+                       return false;
 
-               if (njoinrels >= nbaserel)
-                       break;
+               /*
+                * Delete all join hints which have different combination from Leading
+                * hint.
+                */
+               for (i = 2; i <= njoinrels; i++)
+               {
+                       list_free(hstate->join_hint_level[i]);
+
+                       hstate->join_hint_level[i] = lappend(NIL, join_method_hints[i]);
+               }
        }
+       else
+       {
+               joinrelids = OuterInnerJoinCreate(lhint->outer_inner,
+                                                                                 lhint,
+                                          root,
+                                          initial_rels,
+                                                                                 hstate,
+                                                                                 nbaserel);
 
-       bms_free(joinrelids);
+               njoinrels = bms_num_members(joinrelids);
+               Assert(njoinrels >= 2);
 
-       if (njoinrels < 2)
-               return;
+               /*
+                * Delete all join hints which have different combination from Leading
+                * hint.
+                */
+               for (i = 2;i <= njoinrels; i++)
+               {
+                       if (hstate->join_hint_level[i] != NIL)
+                       {
+                               ListCell *next = NULL;
+                               for(l = list_head(hstate->join_hint_level[i]); l; l = next)
+                               {
 
-       /*
-        * Delete all join hints which have different combination from Leading
-        * hint.
-        */
-       for (i = 2; i <= njoinrels; i++)
-       {
-               list_free(hstate->join_hint_level[i]);
+                                       JoinMethodHint *hint = (JoinMethodHint *)lfirst(l);
+
+                                       next = lnext(hstate->join_hint_level[i], l);
+
+                                       if (hint->inner_nrels == 0 &&
+                                               !(bms_intersect(hint->joinrelids, joinrelids) == NULL ||
+                                                 bms_equal(bms_union(hint->joinrelids, joinrelids),
+                                                 hint->joinrelids)))
+                                       {
+                                               hstate->join_hint_level[i] =
+                                                       list_delete_cell(hstate->join_hint_level[i], l);
+                                               /*
+                                                * The cells after the deleted cell have been moved
+                                                * towards the list head by 1 element.  the next
+                                                * iteration should visit the cell at the same address
+                                                * if any.
+                                                */
+                                               if (next)
+                                                       next = l;
+                                       }
+                               }
+                       }
+               }
 
-               hstate->join_hint_level[i] = lappend(NIL, join_method_hints[i]);
+               bms_free(joinrelids);
        }
 
        if (hint_state_enabled(lhint))
-               set_join_config_options(DISABLE_ALL_JOIN, current_hint->context);
-
-       lhint->base.state = HINT_STATE_USED;
-
+       {
+               set_join_config_options(DISABLE_ALL_JOIN, false,
+                                                               current_hint_state->context);
+               return true;
+       }
+       return false;
 }
 
 /*
- * set_plain_rel_pathlist
- *       Build access paths for a plain relation (no subquery, no inheritance)
+ * wrapper of make_join_rel()
  *
- * This function was copied and edited from set_plain_rel_pathlist() in
- * src/backend/optimizer/path/allpaths.c
+ * call make_join_rel() after changing enable_* parameters according to given
+ * hints.
  */
-static void
-set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
+static RelOptInfo *
+make_join_rel_wrapper(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
 {
-       /* Consider sequential scan */
-#if PG_VERSION_NUM >= 90200
-       add_path(rel, create_seqscan_path(root, rel, NULL));
-#else
-       add_path(rel, create_seqscan_path(root, rel));
-#endif
-
-       /* Consider index scans */
-       create_index_paths(root, rel);
-
-       /* Consider TID scans */
-       create_tidscan_paths(root, rel);
+       Relids                  joinrelids;
+       JoinMethodHint *join_hint;
+       JoinMethodHint *memoize_hint;
+       RelOptInfo         *rel;
+       int                             save_nestlevel;
 
-       /* Now find the cheapest of the paths for this rel */
-       set_cheapest(rel);
-}
+       joinrelids = bms_union(rel1->relids, rel2->relids);
+       join_hint = find_join_hint(joinrelids);
+       memoize_hint = find_memoize_hint(joinrelids);
+       bms_free(joinrelids);
 
-static void
-rebuild_scan_path(HintState *hstate, PlannerInfo *root, int level,
-                                 List *initial_rels)
-{
-       ListCell   *l;
+       /* reject non-matching hints */
+       if (join_hint && join_hint->inner_nrels != 0)
+               join_hint = NULL;
+       
+       if (memoize_hint && memoize_hint->inner_nrels != 0)
+               memoize_hint = NULL;
 
-       foreach(l, initial_rels)
+       if (join_hint || memoize_hint)
        {
-               RelOptInfo         *rel = (RelOptInfo *) lfirst(l);
-               RangeTblEntry  *rte;
-               ScanMethodHint *hint;
-
-               /* Skip relations which we can't choose scan method. */
-               if (rel->reloptkind != RELOPT_BASEREL || rel->rtekind != RTE_RELATION)
-                       continue;
-
-               rte = root->simple_rte_array[rel->relid];
+               save_nestlevel = NewGUCNestLevel();
 
-               /* We can't force scan method of foreign tables */
-               if (rte->relkind == RELKIND_FOREIGN_TABLE)
-                       continue;
+               if (join_hint)
+                       set_join_config_options(join_hint->enforce_mask, false,
+                                                                       current_hint_state->context);
 
-               /*
-                * Create scan paths with GUC parameters which are at the beginning of
-                * planner if scan method hint is not specified, otherwise use
-                * specified hints and mark the hint as used.
-                */
-               if ((hint = find_scan_hint(root, rel)) == NULL)
-                       set_scan_config_options(hstate->init_scan_mask,
-                                                                       hstate->context);
-               else
+               if (memoize_hint)
                {
-                       set_scan_config_options(hint->enforce_mask, hstate->context);
-                       hint->base.state = HINT_STATE_USED;
+                       bool memoize =
+                               memoize_hint->base.hint_keyword == HINT_KEYWORD_MEMOIZE;
+                       set_config_option_noerror("enable_memoize",
+                                                                         memoize ? "true" : "false",
+                                                                         current_hint_state->context,
+                                                                         PGC_S_SESSION, GUC_ACTION_SAVE,
+                                                                         true, ERROR);
                }
+       }
 
-               list_free_deep(rel->pathlist);
-               rel->pathlist = NIL;
-               if (rte->inh)
-               {
-                       /* It's an "append relation", process accordingly */
-                       set_append_rel_pathlist(root, rel, rel->relid, rte);
-               }
-               else
-               {
-                       set_plain_rel_pathlist(root, rel, rte);
-               }
+       /* do the work */
+       rel = pg_hint_plan_make_join_rel(root, rel1, rel2);
+
+       /* Restore the GUC variables we set above. */
+       if (join_hint || memoize_hint)
+       {
+               if (join_hint)
+                       join_hint->base.state = HINT_STATE_USED;
+
+               if (memoize_hint)
+                       memoize_hint->base.state = HINT_STATE_USED;
+
+               AtEOXact_GUC(true, save_nestlevel);
        }
 
-       /*
-        * Restore the GUC variables we set above.
-        */
-       set_scan_config_options(hstate->init_scan_mask, hstate->context);
+       return rel;
 }
 
 /*
- * wrapper of make_join_rel()
- *
- * call make_join_rel() after changing enable_* parameters according to given
- * hints.
+ * TODO : comment
  */
-static RelOptInfo *
-make_join_rel_wrapper(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
+static void
+add_paths_to_joinrel_wrapper(PlannerInfo *root,
+                                                        RelOptInfo *joinrel,
+                                                        RelOptInfo *outerrel,
+                                                        RelOptInfo *innerrel,
+                                                        JoinType jointype,
+                                                        SpecialJoinInfo *sjinfo,
+                                                        List *restrictlist)
 {
        Relids                  joinrelids;
-       JoinMethodHint *hint;
-       RelOptInfo         *rel;
+       JoinMethodHint *join_hint;
+       JoinMethodHint *memoize_hint;
        int                             save_nestlevel;
 
-       joinrelids = bms_union(rel1->relids, rel2->relids);
-       hint = find_join_hint(joinrelids);
+       joinrelids = bms_union(outerrel->relids, innerrel->relids);
+       join_hint = find_join_hint(joinrelids);
+       memoize_hint = find_memoize_hint(joinrelids);
        bms_free(joinrelids);
 
-       if (!hint)
-               return pg_hint_plan_make_join_rel(root, rel1, rel2);
+       /* reject the found hints if they don't match this join */
+       if (join_hint && join_hint->inner_nrels == 0)
+               join_hint = NULL;
 
-       save_nestlevel = NewGUCNestLevel();
+       if (memoize_hint && memoize_hint->inner_nrels == 0)
+               memoize_hint = NULL;
 
-       set_join_config_options(hint->enforce_mask, current_hint->context);
+       /* set up configuration if needed */
+       if (join_hint || memoize_hint)
+       {
+               save_nestlevel = NewGUCNestLevel();
 
-       rel = pg_hint_plan_make_join_rel(root, rel1, rel2);
-       hint->base.state = HINT_STATE_USED;
+               if (join_hint)
+               {
+                       if (bms_equal(join_hint->inner_joinrelids, innerrel->relids))
+                               set_join_config_options(join_hint->enforce_mask, false,
+                                                                               current_hint_state->context);
+                       else
+                               set_join_config_options(DISABLE_ALL_JOIN, false,
+                                                                               current_hint_state->context);
+               }
 
-       /*
-        * Restore the GUC variables we set above.
-        */
-       AtEOXact_GUC(true, save_nestlevel);
+               if (memoize_hint)
+               {
+                       bool memoize =
+                               memoize_hint->base.hint_keyword == HINT_KEYWORD_MEMOIZE;
+                       set_config_option_noerror("enable_memoize",
+                                                                         memoize ? "true" : "false",
+                                                                         current_hint_state->context,
+                                                                         PGC_S_SESSION, GUC_ACTION_SAVE,
+                                                                         true, ERROR);
+               }
+       }
 
-       return rel;
+       /* generate paths */
+       add_paths_to_joinrel(root, joinrel, outerrel, innerrel, jointype,
+                                                sjinfo, restrictlist);
+
+       /* restore GUC variables */
+       if (join_hint || memoize_hint)
+       {
+               if (join_hint)
+                       join_hint->base.state = HINT_STATE_USED;
+
+               if (memoize_hint)
+                       memoize_hint->base.state = HINT_STATE_USED;
+
+               AtEOXact_GUC(true, save_nestlevel);
+       }
 }
 
 static int
@@ -2414,16 +4568,18 @@ static RelOptInfo *
 pg_hint_plan_join_search(PlannerInfo *root, int levels_needed,
                                                 List *initial_rels)
 {
-       JoinMethodHint **join_method_hints;
-       int                     nbaserel;
-       RelOptInfo *rel;
-       int                     i;
+       JoinMethodHint    **join_method_hints;
+       int                                     nbaserel;
+       RelOptInfo                 *rel;
+       int                                     i;
+       bool                            leading_hint_enable;
 
        /*
         * Use standard planner (or geqo planner) if pg_hint_plan is disabled or no
-        * valid hint is supplied.
+        * valid hint is supplied or current nesting depth is nesting depth of SPI
+        * calls.
         */
-       if (!current_hint)
+       if (!current_hint_state || hint_inhibit_level > 0)
        {
                if (prev_join_search)
                        return (*prev_join_search) (root, levels_needed, initial_rels);
@@ -2433,9 +4589,6 @@ pg_hint_plan_join_search(PlannerInfo *root, int levels_needed,
                        return standard_join_search(root, levels_needed, initial_rels);
        }
 
-       /* We apply scan method hint rebuild scan path. */
-       rebuild_scan_path(current_hint, root, levels_needed, initial_rels);
-
        /*
         * In the case using GEQO, only scan method hints and Set hints have
         * effect.  Join method and join order is not controllable by hints.
@@ -2444,75 +4597,306 @@ pg_hint_plan_join_search(PlannerInfo *root, int levels_needed,
                return geqo(root, levels_needed, initial_rels);
 
        nbaserel = get_num_baserels(initial_rels);
-       current_hint->join_hint_level = palloc0(sizeof(List *) * (nbaserel + 1));
+       current_hint_state->join_hint_level =
+               palloc0(sizeof(List *) * (nbaserel + 1));
        join_method_hints = palloc0(sizeof(JoinMethodHint *) * (nbaserel + 1));
+       current_hint_state->memoize_hint_level =
+               palloc0(sizeof(List *) * (nbaserel + 1));
 
-       transform_join_hints(current_hint, root, nbaserel, initial_rels,
-                                                join_method_hints);
+       leading_hint_enable = transform_join_hints(current_hint_state,
+                                                                                          root, nbaserel,
+                                                                                          initial_rels, join_method_hints);
 
        rel = pg_hint_plan_standard_join_search(root, levels_needed, initial_rels);
 
+       /*
+        * Adjust number of parallel workers of the result rel to the largest
+        * number of the component paths.
+        */
+       if (current_hint_state->num_hints[HINT_TYPE_PARALLEL] > 0)
+       {
+               ListCell   *lc;
+               int             nworkers = 0;
+       
+               foreach (lc, initial_rels)
+               {
+                       ListCell *lcp;
+                       RelOptInfo *rel = (RelOptInfo *) lfirst(lc);
+
+                       foreach (lcp, rel->partial_pathlist)
+                       {
+                               Path *path = (Path *) lfirst(lcp);
+
+                               if (nworkers < path-> parallel_workers)
+                                       nworkers = path-> parallel_workers;
+                       }
+               }
+
+               foreach (lc, rel->partial_pathlist)
+               {
+                       Path *path = (Path *) lfirst(lc);
+
+                       if (path->parallel_safe && path->parallel_workers < nworkers)
+                               path->parallel_workers = nworkers;
+               }
+       }
+
        for (i = 2; i <= nbaserel; i++)
        {
-               list_free(current_hint->join_hint_level[i]);
+               list_free(current_hint_state->join_hint_level[i]);
 
                /* free Leading hint only */
                if (join_method_hints[i] != NULL &&
                        join_method_hints[i]->enforce_mask == ENABLE_ALL_JOIN)
                        JoinMethodHintDelete(join_method_hints[i]);
        }
-       pfree(current_hint->join_hint_level);
+       pfree(current_hint_state->join_hint_level);
        pfree(join_method_hints);
 
-       if (current_hint->num_hints[HINT_TYPE_LEADING] > 0 &&
-               hint_state_enabled(current_hint->leading_hint))
-               set_join_config_options(current_hint->init_join_mask,
-                                                               current_hint->context);
+       if (leading_hint_enable)
+               set_join_config_options(current_hint_state->init_join_mask, true,
+                                                               current_hint_state->context);
 
        return rel;
 }
 
 /*
- * set_rel_pathlist
- *       Build access paths for a base relation
- *
- * This function was copied and edited from set_rel_pathlist() in
- * src/backend/optimizer/path/allpaths.c
+ * Force number of wokers if instructed by hint
  */
-static void
-set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
-                                Index rti, RangeTblEntry *rte)
+void
+pg_hint_plan_set_rel_pathlist(PlannerInfo * root, RelOptInfo *rel,
+                                                         Index rti, RangeTblEntry *rte)
 {
-#if PG_VERSION_NUM >= 90200
+       ParallelHint   *phint;
+       ListCell           *l;
+       int                             found_hints;
+
+       /* call the previous hook */
+       if (prev_set_rel_pathlist)
+               prev_set_rel_pathlist(root, rel, rti, rte);
+
+       /* Nothing to do if no hint available */
+       if (current_hint_state == NULL)
+               return;
+
+       /* Don't touch dummy rels. */
        if (IS_DUMMY_REL(rel))
+               return;
+
+       /*
+        * We can accept only plain relations, foreign tables and table saples are
+        * also unacceptable. See set_rel_pathlist.
+        */
+       if ((rel->rtekind != RTE_RELATION &&
+                rel->rtekind != RTE_SUBQUERY)||
+               rte->relkind == RELKIND_FOREIGN_TABLE ||
+               rte->tablesample != NULL)
+               return;
+
+       /*
+        * Even though UNION ALL node doesn't have particular name so usually it is
+        * unhintable, turn on parallel when it contains parallel nodes.
+        */
+       if (rel->rtekind == RTE_SUBQUERY)
        {
-               /* We already proved the relation empty, so nothing more to do */
-       }
-       else if (rte->inh)
-#else
-       if (rte->inh)
-#endif
-       {
-               /* It's an "append relation", process accordingly */
-               set_append_rel_pathlist(root, rel, rti, rte);
+               ListCell *lc;
+               bool    inhibit_nonparallel = false;
+
+               if (rel->partial_pathlist == NIL)
+                       return;
+
+               foreach(lc, rel->partial_pathlist)
+               {
+                       ListCell *lcp;
+                       AppendPath *apath = (AppendPath *) lfirst(lc);
+                       int             parallel_workers = 0;
+
+                       if (!IsA(apath, AppendPath))
+                               continue;
+
+                       foreach (lcp, apath->subpaths)
+                       {
+                               Path *spath = (Path *) lfirst(lcp);
+
+                               if (spath->parallel_aware &&
+                                       parallel_workers < spath->parallel_workers)
+                                       parallel_workers = spath->parallel_workers;
+                       }
+
+                       apath->path.parallel_workers = parallel_workers;
+                       inhibit_nonparallel = true;
+               }
+
+               if (inhibit_nonparallel)
+               {
+                       ListCell *lc;
+
+                       foreach(lc, rel->pathlist)
+                       {
+                               Path *path = (Path *) lfirst(lc);
+
+                               if (path->startup_cost < disable_cost)
+                               {
+                                       path->startup_cost += disable_cost;
+                                       path->total_cost += disable_cost;
+                               }
+                       }
+               }
+
+               return;
        }
-       else
+
+       /* We cannot handle if this requires an outer */
+       if (rel->lateral_relids)
+               return;
+
+       /* Return if this relation gets no enfocement */
+       if ((found_hints = setup_hint_enforcement(root, rel, NULL, &phint)) == 0)
+               return;
+
+       /* Here, we regenerate paths with the current hint restriction */
+       if (found_hints & HINT_BM_SCAN_METHOD || found_hints & HINT_BM_PARALLEL)
        {
-               if (rel->rtekind == RTE_RELATION)
+               /*
+                * When hint is specified on non-parent relations, discard existing
+                * paths and regenerate based on the hint considered. Otherwise we
+                * already have hinted childx paths then just adjust the number of
+                * planned number of workers.
+                */
+               if (root->simple_rte_array[rel->relid]->inh)
                {
-                       if (rte->relkind == RELKIND_RELATION)
+                       /* enforce number of workers if requested */
+                       if (phint && phint->force_parallel)
                        {
-                               /* Plain relation */
-                               set_plain_rel_pathlist(root, rel, rte);
+                               if (phint->nworkers == 0)
+                               {
+                                       list_free_deep(rel->partial_pathlist);
+                                       rel->partial_pathlist = NIL;
+                               }
+                               else
+                               {
+                                       /* prioritize partial paths */
+                                       foreach (l, rel->partial_pathlist)
+                                       {
+                                               Path *ppath = (Path *) lfirst(l);
+
+                                               if (ppath->parallel_safe)
+                                               {
+                                                       ppath->parallel_workers = phint->nworkers;
+                                                       ppath->startup_cost = 0;
+                                                       ppath->total_cost = 0;
+                                               }
+                                       }
+
+                                       /* disable non-partial paths */
+                                       foreach (l, rel->pathlist)
+                                       {
+                                               Path *ppath = (Path *) lfirst(l);
+
+                                               if (ppath->startup_cost < disable_cost)
+                                               {
+                                                       ppath->startup_cost += disable_cost;
+                                                       ppath->total_cost += disable_cost;
+                                               }
+                                       }
+                               }
                        }
-                       else
-                               elog(ERROR, "unexpected relkind: %c", rte->relkind);
                }
                else
-                       elog(ERROR, "unexpected rtekind: %d", (int) rel->rtekind);
+               {
+                       /* Just discard all the paths considered so far */
+                       list_free_deep(rel->pathlist);
+                       rel->pathlist = NIL;
+                       list_free_deep(rel->partial_pathlist);
+                       rel->partial_pathlist = NIL;
+
+                       /* Regenerate paths with the current enforcement */
+                       set_plain_rel_pathlist(root, rel, rte);
+
+                       /* Additional work to enforce parallel query execution */
+                       if (phint && phint->nworkers > 0)
+                       {
+                               /*
+                                * For Parallel Append to be planned properly, we shouldn't set
+                                * the costs of non-partial paths to disable-value.  Lower the
+                                * priority of non-parallel paths by setting partial path costs
+                                * to 0 instead.
+                                */
+                               foreach (l, rel->partial_pathlist)
+                               {
+                                       Path *path = (Path *) lfirst(l);
+
+                                       path->startup_cost = 0;
+                                       path->total_cost = 0;
+                               }
+
+                               /* enforce number of workers if requested */
+                               if (phint->force_parallel)
+                               {
+                                       foreach (l, rel->partial_pathlist)
+                                       {
+                                               Path *ppath = (Path *) lfirst(l);
+
+                                               if (ppath->parallel_safe)
+                                                       ppath->parallel_workers = phint->nworkers;
+                                       }
+                               }
+
+                               /* Generate gather paths */
+                               if (rel->reloptkind == RELOPT_BASEREL &&
+                                       bms_membership(root->all_baserels) != BMS_SINGLETON)
+                                       generate_gather_paths(root, rel, false);
+                       }
+               }
        }
+
+       reset_hint_enforcement();
+}
+
+/*
+ * stmt_beg callback is called when each query in PL/pgSQL function is about
+ * to be executed.  At that timing, we save query string in the global variable
+ * plpgsql_query_string to use it in planner hook.  It's safe to use one global
+ * variable for the purpose, because its content is only necessary until
+ * planner hook is called for the query, so recursive PL/pgSQL function calls
+ * don't harm this mechanism.
+ */
+static void
+pg_hint_plan_plpgsql_stmt_beg(PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt)
+{
+       plpgsql_recurse_level++;
+}
+
+/*
+ * stmt_end callback is called then each query in PL/pgSQL function has
+ * finished.  At that timing, we clear plpgsql_query_string to tell planner
+ * hook that next call is not for a query written in PL/pgSQL block.
+ */
+static void
+pg_hint_plan_plpgsql_stmt_end(PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt)
+{
+       plpgsql_recurse_level--;
+}
+
+void plpgsql_query_erase_callback(ResourceReleasePhase phase,
+                                                                 bool isCommit,
+                                                                 bool isTopLevel,
+                                                                 void *arg)
+{
+       if (!isTopLevel || phase != RESOURCE_RELEASE_AFTER_LOCKS)
+               return;
+       /* Cancel plpgsql nest level*/
+       plpgsql_recurse_level = 0;
 }
 
+
+/* include core static functions */
+static void populate_joinrel_with_paths(PlannerInfo *root, RelOptInfo *rel1,
+                                                                               RelOptInfo *rel2, RelOptInfo *joinrel,
+                                                                               SpecialJoinInfo *sjinfo, List *restrictlist);
+static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
+                                                                       Index rti, RangeTblEntry *rte);
+
 #define standard_join_search pg_hint_plan_standard_join_search
 #define join_search_one_level pg_hint_plan_join_search_one_level
 #define make_join_rel make_join_rel_wrapper
@@ -2520,16 +4904,7 @@ set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
 
 #undef make_join_rel
 #define make_join_rel pg_hint_plan_make_join_rel
-#define add_paths_to_joinrel(root, joinrel, outerrel, innerrel, jointype, sjinfo, restrictlist) \
-do { \
-       ScanMethodHint *hint = NULL; \
-       if ((hint = find_scan_hint((root), (innerrel))) != NULL) \
-       { \
-               set_scan_config_options(hint->enforce_mask, current_hint->context); \
-               hint->base.state = HINT_STATE_USED; \
-       } \
-       add_paths_to_joinrel((root), (joinrel), (outerrel), (innerrel), (jointype), (sjinfo), (restrictlist)); \
-       if (hint != NULL) \
-               set_scan_config_options(current_hint->init_scan_mask, current_hint->context); \
-} while(0)
+#define add_paths_to_joinrel add_paths_to_joinrel_wrapper
 #include "make_join_rel.c"
+
+#include "pg_stat_statements.c"