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[pghintplan/pg_hint_plan.git] / pg_hint_plan.c
index ed196c2..87cf0d8 100644 (file)
@@ -4,11 +4,12 @@
  *               do instructions or hints to the planner using C-style block comments
  *               of the SQL.
  *
- * Copyright (c) 2012, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
+ * Copyright (c) 2012-2013, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_index.h"
 #include "commands/prepare.h"
 #include "mb/pg_wchar.h"
 #include "optimizer/restrictinfo.h"
 #include "parser/scansup.h"
 #include "tcop/utility.h"
+#include "utils/builtins.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/rel.h"
+#include "utils/syscache.h"
+#include "utils/resowner.h"
 #if PG_VERSION_NUM >= 90200
 #include "catalog/pg_class.h"
 #endif
 
+#include "executor/spi.h"
+#include "catalog/pg_type.h"
+/*
+ * We have our own header file "plpgsql-9.1", which is necessary to support
+ * hints for queries in PL/pgSQL blocks, in pg_hint_plan source package,
+ * because PostgreSQL 9.1 doesn't provide the header file as a part of
+ * installation.  This header file is a copy of src/pl/plpgsql/src/plpgsql.h in
+ * PostgreSQL 9.1.9 source tree,
+ *
+ * On the other hand, 9.2 installation provides that header file for external
+ * modules, so we include the header in ordinary place.
+ */
+#if PG_VERSION_NUM >= 90200
+#include "plpgsql.h"
+#else
+#include "plpgsql-9.1.h"
+#endif
+
+/* partially copied from pg_stat_statements */
+#include "normalize_query.h"
+
 #ifdef PG_MODULE_MAGIC
 PG_MODULE_MAGIC;
 #endif
@@ -50,7 +75,9 @@ 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"
@@ -58,6 +85,7 @@ PG_MODULE_MAGIC;
 #define HINT_NOTIDSCAN                 "NoTidScan"
 #if PG_VERSION_NUM >= 90200
 #define HINT_INDEXONLYSCAN             "IndexOnlyScan"
+#define HINT_INDEXONLYSCANREGEXP       "IndexOnlyScanRegexp"
 #define HINT_NOINDEXONLYSCAN   "NoIndexOnlyScan"
 #endif
 #define HINT_NESTLOOP                  "NestLoop"
@@ -115,7 +143,9 @@ 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,
@@ -123,6 +153,7 @@ typedef enum HintKeyword
        HINT_KEYWORD_NOTIDSCAN,
 #if PG_VERSION_NUM >= 90200
        HINT_KEYWORD_INDEXONLYSCAN,
+       HINT_KEYWORD_INDEXONLYSCANREGEXP,
        HINT_KEYWORD_NOINDEXONLYSCAN,
 #endif
        HINT_KEYWORD_NESTLOOP,
@@ -198,9 +229,22 @@ 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
 {
@@ -257,7 +301,7 @@ struct HintState
        Index                   parent_relid;           /* inherit parent table relid */
        Oid                             parent_rel_oid;     /* inherit parent table relid */
        ScanMethodHint *parent_hint;            /* inherit parent table scan hint */
-       List               *parent_ind_atts;    /* attnums of inherit parent table's
+       List               *parent_index_infos; /* information of inherit parent table's
                                                                                 * index */
 
        /* for join method hints */
@@ -362,10 +406,21 @@ static void set_dummy_rel_pathlist(RelOptInfo *rel);
 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);
+
 /* 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;
+/* Default is off, to keep backward compatibility. */
+static bool    pg_hint_plan_enable_hint_table = false;
 
 static const struct config_enum_entry parse_messages_level_options[] = {
        {"debug", DEBUG2, true},
@@ -410,7 +465,10 @@ 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},
@@ -418,6 +476,8 @@ static const HintParser parsers[] = {
        {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},
@@ -432,11 +492,33 @@ static const HintParser parsers[] = {
 };
 
 /*
+ * PL/pgSQL plugin for retrieving string representation of each query during
+ * function execution.
+ */
+static const char *plpgsql_query_string = NULL;
+static enum PLpgSQL_stmt_types plpgsql_query_string_src;
+
+PLpgSQL_plugin  plugin_funcs = {
+       NULL,
+       NULL,
+       NULL,
+       pg_hint_plan_plpgsql_stmt_beg,
+       pg_hint_plan_plpgsql_stmt_end,
+       NULL,
+       NULL,
+};
+
+/* Current nesting depth of SPI calls, used to prevent recursive calls */
+static int     nested_level = 0;
+
+/*
  * 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.",
@@ -472,6 +554,17 @@ _PG_init(void)
                                                         NULL,
                                                         NULL);
 
+       DefineCustomBoolVariable("pg_hint_plan.enable_hint_table",
+                                        "Force planner to not get hint by using table lookups.",
+                                                        NULL,
+                                                        &pg_hint_plan_enable_hint_table,
+                                                        false,
+                                                        PGC_USERSET,
+                                                        0,
+                                                        NULL,
+                                                        NULL,
+                                                        NULL);
+
        /* Install hooks. */
        prev_ProcessUtility = ProcessUtility_hook;
        ProcessUtility_hook = pg_hint_plan_ProcessUtility;
@@ -481,6 +574,12 @@ _PG_init(void)
        get_relation_info_hook = pg_hint_plan_get_relation_info;
        prev_join_search = join_search_hook;
        join_search_hook = pg_hint_plan_join_search;
+
+       /* setup PL/pgSQL plugin hook */
+       var_ptr = (PLpgSQL_plugin **) find_rendezvous_variable("PLpgSQL_plugin");
+       *var_ptr = &plugin_funcs;
+
+       RegisterResourceReleaseCallback(plpgsql_query_erase_callback, NULL);
 }
 
 /*
@@ -490,11 +589,17 @@ _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;
+
+       /* uninstall PL/pgSQL plugin hook */
+       var_ptr = (PLpgSQL_plugin **) find_rendezvous_variable("PLpgSQL_plugin");
+       *var_ptr = NULL;
 }
 
 /*
@@ -519,6 +624,7 @@ ScanMethodHintCreate(const char *hint_str, const char *keyword,
        hint->base.parse_func = (HintParseFunction) ScanMethodHintParse;
        hint->relname = NULL;
        hint->indexnames = NIL;
+       hint->regexp = false;
        hint->enforce_mask = 0;
 
        return (Hint *) hint;
@@ -670,7 +776,7 @@ HintStateCreate(void)
        hstate->parent_relid = 0;
        hstate->parent_rel_oid = InvalidOid;
        hstate->parent_hint = NULL;
-       hstate->parent_ind_atts = NIL;
+       hstate->parent_index_infos = NIL;
        hstate->join_hints = NULL;
        hstate->init_join_mask = 0;
        hstate->join_hint_level = NULL;
@@ -696,8 +802,8 @@ HintStateDelete(HintState *hstate)
                hstate->all_hints[i]->delete_func(hstate->all_hints[i]);
        if (hstate->all_hints)
                pfree(hstate->all_hints);
-       if (hstate->parent_ind_atts)
-               list_free(hstate->parent_ind_atts);
+       if (hstate->parent_index_infos)
+               list_free(hstate->parent_index_infos);
 }
 
 /*
@@ -842,7 +948,7 @@ SetHintDesc(SetHint *hint, StringInfo buf)
 }
 
 /*
- * Append string which repserents all hints in a given state to buf, with
+ * Append string which represents all hints in a given state to buf, with
  * preceding title with them.
  */
 static void
@@ -1180,7 +1286,7 @@ parse_parentheses_Leading(const char *str, List **name_list,
 }
 
 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;
@@ -1202,7 +1308,12 @@ 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 ||
+#if PG_VERSION_NUM >= 90200
+                       keyword == HINT_KEYWORD_INDEXONLYSCANREGEXP ||
+#endif
+                       keyword == HINT_KEYWORD_BITMAPSCANREGEXP ||
+                       keyword == HINT_KEYWORD_SET)
                {
                        truncate = false;
                }
@@ -1287,20 +1398,88 @@ parse_hints(HintState *hstate, Query *parse, const char *str)
        pfree(buf.data);
 }
 
+
+/* 
+ * Get hints from table by client-supplied query string and application name.
+ */
+static const char *
+get_hints_from_table(const char *client_query, const char *client_application)
+{
+       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];
+       bool    nulls[2] = { false, false };
+       text   *qry;
+       text   *app;
+
+       PG_TRY();
+       {
+               ++nested_level;
+       
+               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();
+       
+               --nested_level;
+       }
+       PG_CATCH();
+       {
+               --nested_level;
+               PG_RE_THROW();
+       }
+       PG_END_TRY();
+
+       return hints;
+}
+
 /*
- * Do basic parsing of the query head comment.
+ * Get client-supplied query string.
  */
-static HintState *
-parse_head_comment(Query *parse)
+static const char *
+get_query_string(void)
 {
        const char *p;
-       char       *head;
-       char       *tail;
-       int                     len;
-       int                     i;
-       HintState   *hstate;
 
-       /* get client-supplied query string. */
        if (stmt_name)
        {
                PreparedStatement  *entry;
@@ -1308,18 +1487,57 @@ parse_head_comment(Query *parse)
                entry = FetchPreparedStatement(stmt_name, true);
                p = entry->plansource->query_string;
        }
+       else if (plpgsql_query_string)
+               p = plpgsql_query_string;
        else
                p = debug_query_string;
 
+       return p;
+}
+
+/*
+ * 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;
+       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;
+       }
 
+       len = strlen(HINT_START);
        head = (char *) p;
        p += len;
        skip_space(p);
@@ -1345,8 +1563,25 @@ 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;
+
+       p = hints;
        hstate = HintStateCreate();
-       hstate->hint_str = head;
+       hstate->hint_str = (char *) hints;
 
        /* parse each hint. */
        parse_hints(hstate, parse, p);
@@ -1371,7 +1606,7 @@ 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++)
@@ -1425,7 +1660,7 @@ 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. */
@@ -1436,12 +1671,15 @@ ScanMethodHintParse(ScanMethodHint *hint, HintState *hstate, Query *parse,
                hint->indexnames = list_delete_first(name_list);
 
                /* check whether the hint accepts index name(s). */
-               if (hint_keyword != HINT_KEYWORD_INDEXSCAN &&
+               if (length != 1 &&
+                       hint_keyword != HINT_KEYWORD_INDEXSCAN &&
+                       hint_keyword != HINT_KEYWORD_INDEXSCANREGEXP &&
 #if PG_VERSION_NUM >= 90200
                        hint_keyword != HINT_KEYWORD_INDEXONLYSCAN &&
+                       hint_keyword != HINT_KEYWORD_INDEXONLYSCANREGEXP &&
 #endif
                        hint_keyword != HINT_KEYWORD_BITMAPSCAN &&
-                       length != 1)
+                       hint_keyword != HINT_KEYWORD_BITMAPSCANREGEXP)
                {
                        hint_ereport(str,
                                                 ("%s hint accepts only one relation.",
@@ -1468,9 +1706,17 @@ 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;
@@ -1490,6 +1736,10 @@ ScanMethodHintParse(ScanMethodHint *hint, HintState *hstate, Query *parse,
                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;
@@ -1511,7 +1761,7 @@ 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);
@@ -1666,7 +1916,8 @@ 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;
@@ -1814,7 +2065,11 @@ pg_hint_plan_ProcessUtility(Node *parsetree, const char *queryString,
 {
        Node                               *node;
 
-       if (!pg_hint_plan_enable_hint)
+       /* 
+        * Use standard planner if pg_hint_plan is disabled or current nesting 
+        * depth is nesting depth of SPI calls. 
+        */
+       if (!pg_hint_plan_enable_hint || nested_level > 0)
        {
                if (prev_ProcessUtility)
                        (*prev_ProcessUtility) (parsetree, queryString, params,
@@ -1946,26 +2201,73 @@ pop_hint(void)
 static PlannedStmt *
 pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 {
+       const char         *hints = NULL;
+       const char         *query;
+       char               *norm_query;
+       pgssJumbleState jstate;
+       int                             query_len;
        int                             save_nestlevel;
        PlannedStmt        *result;
        HintState          *hstate;
 
        /*
-        * 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 if any, so set it to NULL.
         */
-       if (!pg_hint_plan_enable_hint)
-       {
-               current_hint = NULL;
+       if (!pg_hint_plan_enable_hint || nested_level > 0)
+               goto standard_planner_proc;
 
-               if (prev_planner)
-                       return (*prev_planner) (parse, cursorOptions, boundParams);
-               else
-                       return standard_planner(parse, cursorOptions, boundParams);
-       }
+       /* Create hint struct from client-supplied query string. */
+       query = get_query_string();
 
-       /* Create hint struct from parse tree. */
-       hstate = parse_head_comment(parse);
+       /*
+        * Create hintstate from hint specified for the query, if any.
+        *
+        * First we lookup hint in pg_hint.hints table by normalized query string,
+        * unless pg_hint_plan.enable_hint_table is OFF.
+        * This parameter provides option to avoid overhead of table lookup during
+        * planning.
+        *
+        * If no hint was found, then we try to get hint from special query comment.
+        */
+       if (pg_hint_plan_enable_hint_table)
+       {
+               /*
+                * Search hint information which is stored for the query and the
+                * application.  Query string is normalized before using in condition
+                * in order to allow fuzzy matching.
+                *
+                * XXX: normalizing code is copied from pg_stat_statements.c, so be
+                * careful when supporting PostgreSQL's version up.
+                */
+               jstate.jumble = (unsigned char *) palloc(JUMBLE_SIZE);
+               jstate.jumble_len = 0;
+               jstate.clocations_buf_size = 32;
+               jstate.clocations = (pgssLocationLen *)
+                       palloc(jstate.clocations_buf_size * sizeof(pgssLocationLen));
+               jstate.clocations_count = 0;
+               JumbleQuery(&jstate, parse);
+               /*
+                * generate_normalized_query() copies exact given query_len bytes, so we
+                * add 1 byte for null-termination here.  As comments on
+                * generate_normalized_query says, generate_normalized_query doesn't
+                * take care of null-terminate, but additional 1 byte ensures that '\0'
+                * byte in the source buffer to be copied into norm_query.
+                */
+               query_len = strlen(query) + 1;
+               norm_query = generate_normalized_query(&jstate,
+                                                                                          query,
+                                                                                          &query_len,
+                                                                                          GetDatabaseEncoding());
+               hints = get_hints_from_table(norm_query, application_name);
+               elog(DEBUG1,
+                        "pg_hint_plan: get_hints_from_table [%s][%s]=>[%s]",
+                        norm_query, application_name, hints ? hints : "(none)");
+       }
+       if (hints == NULL)
+               hints = get_hints_from_comment(query);
+       hstate = create_hintstate(parse, hints);
 
        /*
         * Use standard planner if the statement has not valid hint.  Other hook
@@ -1973,14 +2275,7 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
         * NULL.
         */
        if (!hstate)
-       {
-               current_hint = NULL;
-
-               if (prev_planner)
-                       return (*prev_planner) (parse, cursorOptions, boundParams);
-               else
-                       return standard_planner(parse, cursorOptions, boundParams);
-       }
+               goto standard_planner_proc;
 
        /*
         * Push new hint struct to the hint stack to disable previous hint context.
@@ -2046,13 +2341,20 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
        pop_hint();
 
        return result;
+
+standard_planner_proc:
+       current_hint = NULL;
+       if (prev_planner)
+               return (*prev_planner) (parse, cursorOptions, boundParams);
+       else
+               return standard_planner(parse, cursorOptions, boundParams);
 }
 
 /*
  * Return scan method hint which matches given aliasname.
  */
 static ScanMethodHint *
-find_scan_hint(PlannerInfo *root, RelOptInfo *rel)
+find_scan_hint(PlannerInfo *root, Index relid, RelOptInfo *rel)
 {
        RangeTblEntry  *rte;
        int                             i;
@@ -2062,10 +2364,10 @@ find_scan_hint(PlannerInfo *root, RelOptInfo *rel)
         *   - not a base relation
         *   - not an ordinary relation (such as join and subquery)
         */
-       if (rel->reloptkind != RELOPT_BASEREL || rel->rtekind != RTE_RELATION)
+       if (rel && (rel->reloptkind != RELOPT_BASEREL || rel->rtekind != RTE_RELATION))
                return NULL;
 
-       rte = root->simple_rte_array[rel->relid];
+       rte = root->simple_rte_array[relid];
 
        /* We can't force scan method of foreign tables */
        if (rte->relkind == RELKIND_FOREIGN_TABLE)
@@ -2087,6 +2389,33 @@ find_scan_hint(PlannerInfo *root, RelOptInfo *rel)
        return NULL;
 }
 
+/*
+ * 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);
+}
+
 static void
 delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
 {
@@ -2134,7 +2463,15 @@ delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
 
                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 (pg_hint_plan_debug_print)
@@ -2147,46 +2484,165 @@ delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
                        }
                }
 
+               /*
+                * to make the index a candidate when definition of this index is
+                * matched with the index's definition of current_hint.
+                */
                if (OidIsValid(relationObjectId) && !use_index)
                {
-                       int         i;
-                       char       *child_attname = NULL;
-                       char       *parent_attname = NULL;
-
-                       foreach(l, current_hint->parent_ind_atts)
+                       foreach(l, current_hint->parent_index_infos)
                        {
-                               List *attnums = (List *)lfirst(l);
+                               int                                     i;
+                               HeapTuple                       ht_idx;
+                               ParentIndexInfo    *p_info = (ParentIndexInfo *)lfirst(l);
+
+                               /* check to match the parameter of unique */
+                               if (p_info->indisunique != info->unique)
+                                       continue;
+
+                               /* check to match the parameter of index's method */
+                               if (p_info->method != info->relam)
+                                       continue;
 
-                               if ((list_length(attnums)) != info->ncolumns)
+                               /* to check to match the indexkey's configuration */
+                               if ((list_length(p_info->column_names)) !=
+                                        info->ncolumns)
                                        continue;
 
+                               /* check to match the indexkey's configuration */
                                for (i = 0; i < info->ncolumns; i++)
                                {
-                                       child_attname = get_attname(relationObjectId,
+                                       char       *c_attname = NULL;
+                                       char       *p_attname = NULL;
+
+                                       p_attname =
+                                               list_nth(p_info->column_names, i);
+
+                                       /* both are expressions */
+                                       if (info->indexkeys[i] == 0 && !p_attname)
+                                               continue;
+
+                                       /* one's column is expression, the other is not */
+                                       if (info->indexkeys[i] == 0 || !p_attname)
+                                               break;
+
+                                       c_attname = get_attname(relationObjectId,
                                                                                                info->indexkeys[i]);
-                                       parent_attname = get_attname(current_hint->parent_rel_oid,
-                                                                                                list_nth_int(attnums, i));
-                                       if (strcmp(parent_attname, child_attname) != 0)
-                                       {
-                                               use_index = false;
+
+                                       if (strcmp(p_attname, c_attname) != 0)
+                                               break;
+
+                                       if (p_info->indcollation[i] != info->indexcollations[i])
+                                               break;
+
+                                       if (p_info->opclass[i] != info->opcintype[i])
+                                               break;
+
+                                       if (((p_info->indoption[i] & INDOPTION_DESC) != 0) !=
+                                               info->reverse_sort[i])
+                                               break;
+
+                                       if (((p_info->indoption[i] & INDOPTION_NULLS_FIRST) != 0) !=
+                                               info->nulls_first[i])
                                                break;
-                                       }
 
-                                       use_index = true;
                                }
 
-                               if (use_index)
+                               if (i != info->ncolumns)
+                                       continue;
+
+                               if ((p_info->expression_str && (info->indexprs != NIL)) ||
+                                       (p_info->indpred_str && (info->indpred != NIL)))
                                {
-                                       if (pg_hint_plan_debug_print)
+                                       /*
+                                        * Fetch the pg_index tuple by the Oid of the index
+                                        */
+                                       ht_idx = SearchSysCache1(INDEXRELID,
+                                                                                        ObjectIdGetDatum(info->indexoid));
+
+                                       /* check to match the expression's parameter of index */
+                                       if (p_info->expression_str &&
+                                               !heap_attisnull(ht_idx, Anum_pg_index_indexprs))
                                        {
-                                               appendStringInfoCharMacro(&buf, ' ');
-                                               quote_value(&buf, indexname);
+                                               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));
+
+                                               if (strcmp(p_info->expression_str,
+                                                                  text_to_cstring(DatumGetTextP(result))) != 0)
+                                               {
+                                                       /* Clean up */
+                                                       ReleaseSysCache(ht_idx);
+
+                                                       continue;
+                                               }
                                        }
 
-                                       break;
+                                       /* Check to match the predicate's parameter of index */
+                                       if (p_info->indpred_str &&
+                                               !heap_attisnull(ht_idx, Anum_pg_index_indpred))
+                                       {
+                                               Datum       predDatum;
+                                               bool        isnull;
+                                               Datum       result;
+
+                                               /*
+                                                * to change the predicate's parameter of child's
+                                                * index to strings
+                                                */
+                                               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;
+
+                               /* to log the candidate of index */
+                               if (pg_hint_plan_debug_print)
+                               {
+                                       appendStringInfoCharMacro(&buf, ' ');
+                                       quote_value(&buf, indexname);
+                               }
+
+                               break;
                        }
                }
+
                if (!use_index)
                        rel->indexlist = list_delete_cell(rel->indexlist, cell, prev);
                else
@@ -2218,34 +2674,213 @@ delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
        }
 }
 
+/* 
+ * Return information of index definition.
+ */
+static ParentIndexInfo *
+get_parent_index_info(Oid indexoid, Oid relid)
+{
+       ParentIndexInfo *p_info = palloc(sizeof(ParentIndexInfo));
+       Relation            indexRelation;
+       Form_pg_index   index;
+       char               *attname;
+       int                             i;
+
+       indexRelation = index_open(indexoid, RowExclusiveLock);
+
+       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);
+
+       for (i = 0; i < index->indnatts; i++)
+       {
+               attname = get_attname(relid, index->indkey.values[i]);
+               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))
+       {
+               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))
+       {
+               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;
+}
+
 static void
 pg_hint_plan_get_relation_info(PlannerInfo *root, Oid relationObjectId,
                                                           bool inhparent, RelOptInfo *rel)
 {
-       ScanMethodHint *hint;
+       ScanMethodHint *hint = NULL;
 
        if (prev_get_relation_info)
                (*prev_get_relation_info) (root, relationObjectId, inhparent, rel);
 
-       /* Do nothing if we don't have valid hint in this context. */
-       if (!current_hint)
+       /* 
+        * Do nothing if we don't have valid hint in this context or current 
+        * nesting depth is nesting depth of SPI calls.
+        */
+       if (!current_hint || nested_level > 0)
                return;
 
        if (inhparent)
        {
                /* store does relids of parent table. */
                current_hint->parent_relid = rel->relid;
-               current_hint->parent_rel_oid = relationObjectId;
+               
+       }
+       else
+       {
+               /*
+                * Inheritance planner doesn't request information for the parent
+                * relation so we should check if this relation has a parent. We can
+                * ignore nested inheritace case because inheritance planner doesn't
+                * meet it.
+                */
+               ListCell *l;
+               foreach (l, root->append_rel_list)
+               {
+                       AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
+
+                       if (appinfo->child_relid == rel->relid)
+                       {
+                               if (current_hint->parent_relid != appinfo->parent_relid)
+                               {
+                                       inhparent = true;
+                                       current_hint->parent_relid = appinfo->parent_relid;
+                               }
+                               break;
+                       }
+               }
+
+       }
+
+       if (inhparent)
+       {
+               Relation    parent_rel;
+               List       *indexoidlist;
+               ListCell   *l;
+               Oid                     parentrel_oid;
+
+               /*
+                * Get and apply the hint for theparent_rel if the new parent has been
+                * found. This relation should be an ordinary relation so calling
+                * find_scan_hint with rel == NULL is safe.
+                */
+               if ((hint = find_scan_hint(root, current_hint->parent_relid,
+                                                                  NULL)) == NULL)
+               {
+                       set_scan_config_options(current_hint->init_scan_mask,
+                                                                       current_hint->context);
+               }
+               else
+               {
+                       set_scan_config_options(hint->enforce_mask,     current_hint->context);
+                       hint->base.state = HINT_STATE_USED;
+               }
+
+               current_hint->parent_hint = hint;
+
+               /* Resolve index name mask (if any) using this parent. */
+               if (hint && hint->indexnames)
+               {
+                       parentrel_oid =
+                               root->simple_rte_array[current_hint->parent_relid]->relid;
+                       parent_rel = heap_open(parentrel_oid, NoLock);
+
+                       /*
+                        * Search for indexes match the hint for this parent
+                        */
+                       indexoidlist = RelationGetIndexList(parent_rel);
+
+                       foreach(l, indexoidlist)
+                       {
+                               Oid         indexoid = lfirst_oid(l);
+                               char       *indexname = get_rel_name(indexoid);
+                               bool        use_index = false;
+                               ListCell   *lc;
+                               ParentIndexInfo *parent_index_info;
+
+                               foreach(lc, hint->indexnames)
+                               {
+                                       if (RelnameCmp(&indexname, &lfirst(lc)) == 0)
+                                       {
+                                               use_index = true;
+                                               break;
+                                       }
+                               }
+                               if (!use_index)
+                                       continue;
+
+                               parent_index_info = get_parent_index_info(indexoid,
+                                                                                                                 parentrel_oid);
+                               current_hint->parent_index_infos =
+                                       lappend(current_hint->parent_index_infos, parent_index_info);
+                       }
+                       heap_close(parent_rel, NoLock);
+               }
+
+               if (current_hint->parent_relid == rel->relid)
+               {
+                       /* This rel is a inheritance parent, which won't be scanned. */
+                       return;
+               }
        }
-       else if (current_hint->parent_relid != 0)
+
+       if (current_hint->parent_hint != 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.
+                * If inheritance parent is registered, check if it is really my
+                * parent.
                 */
                ListCell   *l;
 
-               /* append_rel_list contains all append rels; ignore others */
                foreach(l, root->append_rel_list)
                {
                        AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
@@ -2258,21 +2893,19 @@ pg_hint_plan_get_relation_info(PlannerInfo *root, Oid relationObjectId,
                                        delete_indexes(current_hint->parent_hint, rel,
                                                                   relationObjectId);
 
+                               /* Scan fixation status is the same to the parent. */
                                return;
                        }
                }
 
-               /* This rel is not inherit table. */
+               /* This rel is not a child of the current parent. */
                current_hint->parent_relid = 0;
                current_hint->parent_rel_oid = InvalidOid;
                current_hint->parent_hint = NULL;
        }
 
-       /*
-        * 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)
+       /* This table doesn't have a parent. Apply its own hints */
+       if ((hint = find_scan_hint(root, rel->relid, rel)) == NULL)
        {
                set_scan_config_options(current_hint->init_scan_mask,
                                                                current_hint->context);
@@ -2281,55 +2914,7 @@ pg_hint_plan_get_relation_info(PlannerInfo *root, Oid relationObjectId,
        set_scan_config_options(hint->enforce_mask, current_hint->context);
        hint->base.state = HINT_STATE_USED;
 
-       if (inhparent)
-       {
-               Relation    relation;
-               List       *indexoidlist;
-               ListCell   *l;
-
-               current_hint->parent_hint = hint;
-
-               relation = heap_open(relationObjectId, NoLock);
-               indexoidlist = RelationGetIndexList(relation);
-
-               foreach(l, indexoidlist)
-               {
-                       int         i;
-                       Oid         indexoid = lfirst_oid(l);
-                       char       *indexname = get_rel_name(indexoid);
-                       bool        use_index = false;
-                       Relation    indexRelation;
-                       Form_pg_index index;
-                       ListCell   *lc;
-                       List       *attnums = NIL;
-
-                       foreach(lc, hint->indexnames)
-                       {
-                               if (RelnameCmp(&indexname, &lfirst(lc)) == 0)
-                               {
-                                       use_index = true;
-                                       break;
-                               }
-                       }
-                       if (!use_index)
-                               continue;
-
-                       indexRelation = index_open(indexoid, RowExclusiveLock);
-
-                       index = indexRelation->rd_index;
-
-                       for (i = 0; i < index->indnatts; i++)
-                                attnums = lappend_int(attnums, index->indkey.values[i]);
-
-                       current_hint->parent_ind_atts =
-                               lappend(current_hint->parent_ind_atts, attnums);
-
-                       index_close(indexRelation, NoLock);
-               }
-               heap_close(relation, NoLock);
-       }
-       else
-               delete_indexes(hint, rel, InvalidOid);
+       delete_indexes(hint, rel, InvalidOid);
 }
 
 /*
@@ -2798,7 +3383,7 @@ rebuild_scan_path(HintState *hstate, PlannerInfo *root, int level,
                 * 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)
+               if ((hint = find_scan_hint(root, rel->relid, rel)) == NULL)
                        set_scan_config_options(hstate->init_scan_mask,
                                                                        hstate->context);
                else
@@ -2884,7 +3469,7 @@ add_paths_to_joinrel_wrapper(PlannerInfo *root,
        JoinMethodHint *join_hint;
        int                             save_nestlevel;
 
-       if ((scan_hint = find_scan_hint(root, innerrel)) != NULL)
+       if ((scan_hint = find_scan_hint(root, innerrel->relid, innerrel)) != NULL)
        {
                set_scan_config_options(scan_hint->enforce_mask, current_hint->context);
                scan_hint->base.state = HINT_STATE_USED;
@@ -2965,9 +3550,10 @@ pg_hint_plan_join_search(PlannerInfo *root, int levels_needed,
 
        /*
         * 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 || nested_level > 0)
        {
                if (prev_join_search)
                        return (*prev_join_search) (root, levels_needed, initial_rels);
@@ -3056,6 +3642,85 @@ set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
        }
 }
 
+/*
+ * 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_expr *expr = NULL;
+
+       switch ((enum PLpgSQL_stmt_types) stmt->cmd_type)
+       {
+               case PLPGSQL_STMT_FORS:
+                       expr = ((PLpgSQL_stmt_fors *) stmt)->query;
+                       break;
+               case PLPGSQL_STMT_FORC:
+                               expr = ((PLpgSQL_var *) (estate->datums[((PLpgSQL_stmt_forc *)stmt)->curvar]))->cursor_explicit_expr;
+                       break;
+               case PLPGSQL_STMT_RETURN_QUERY:
+                       if (((PLpgSQL_stmt_return_query *) stmt)->query != NULL)
+                               expr = ((PLpgSQL_stmt_return_query *) stmt)->query;
+                       else
+                               expr = ((PLpgSQL_stmt_return_query *) stmt)->dynquery;
+                       break;
+               case PLPGSQL_STMT_EXECSQL:
+                       expr = ((PLpgSQL_stmt_execsql *) stmt)->sqlstmt;
+                       break;
+               case PLPGSQL_STMT_DYNEXECUTE:
+                       expr = ((PLpgSQL_stmt_dynexecute *) stmt)->query;
+                       break;
+               case PLPGSQL_STMT_DYNFORS:
+                       expr = ((PLpgSQL_stmt_dynfors *) stmt)->query;
+                       break;
+               case PLPGSQL_STMT_OPEN:
+                       if (((PLpgSQL_stmt_open *) stmt)->query != NULL)
+                               expr = ((PLpgSQL_stmt_open *) stmt)->query;
+                       else if (((PLpgSQL_stmt_open *) stmt)->dynquery != NULL)
+                               expr = ((PLpgSQL_stmt_open *) stmt)->dynquery;
+                       else
+                               expr = ((PLpgSQL_var *) (estate->datums[((PLpgSQL_stmt_open *)stmt)->curvar]))->cursor_explicit_expr;
+                       break;
+               default:
+                       break;
+       }
+
+       if (expr)
+       {
+               plpgsql_query_string = expr->query;
+               plpgsql_query_string_src = (enum PLpgSQL_stmt_types) stmt->cmd_type;
+       }
+}
+
+/*
+ * 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)
+{
+       if (plpgsql_query_string &&
+               plpgsql_query_string_src == stmt->cmd_type)
+               plpgsql_query_string = NULL;
+}
+
+void plpgsql_query_erase_callback(ResourceReleasePhase phase,
+                                                                 bool isCommit,
+                                                                 bool isTopLevel,
+                                                                 void *arg)
+{
+       if (phase != RESOURCE_RELEASE_AFTER_LOCKS)
+               return;
+       /* Force erase stored plpgsql query string */
+       plpgsql_query_string = NULL;
+}
+
 #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
@@ -3065,3 +3730,5 @@ set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
 #define make_join_rel pg_hint_plan_make_join_rel
 #define add_paths_to_joinrel add_paths_to_joinrel_wrapper
 #include "make_join_rel.c"
+
+#include "pg_stat_statements.c"