OSDN Git Service

Remove unused struct member
[pghintplan/pg_hint_plan.git] / pg_hint_plan.c
index 4ae79e3..e8231cd 100644 (file)
@@ -4,7 +4,7 @@
  *               do instructions or hints to the planner using C-style block comments
  *               of the SQL.
  *
- * Copyright (c) 2012-2013, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
+ * Copyright (c) 2012-2014, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
  *
  *-------------------------------------------------------------------------
  */
 #include "utils/memutils.h"
 #include "utils/rel.h"
 #include "utils/syscache.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.
+ */
+#include "plpgsql.h"
+
+/* partially copied from pg_stat_statements */
+#include "normalize_query.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   "+"
@@ -64,11 +74,9 @@ PG_MODULE_MAGIC;
 #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_NESTLOOP                  "NestLoop"
 #define HINT_MERGEJOIN                 "MergeJoin"
 #define HINT_HASHJOIN                  "HashJoin"
@@ -77,6 +85,7 @@ PG_MODULE_MAGIC;
 #define HINT_NOHASHJOIN                        "NoHashJoin"
 #define HINT_LEADING                   "Leading"
 #define HINT_SET                               "Set"
+#define HINT_ROWS                              "Rows"
 
 #define HINT_ARRAY_DEFAULT_INITSIZE 8
 
@@ -95,9 +104,7 @@ enum
        ENABLE_INDEXSCAN = 0x02,
        ENABLE_BITMAPSCAN = 0x04,
        ENABLE_TIDSCAN = 0x08,
-#if PG_VERSION_NUM >= 90200
        ENABLE_INDEXONLYSCAN = 0x10
-#endif
 } SCAN_TYPE_BITS;
 
 enum
@@ -107,14 +114,9 @@ enum
        ENABLE_HASHJOIN = 0x04
 } 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
@@ -132,11 +134,9 @@ typedef enum HintKeyword
        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,
@@ -145,6 +145,7 @@ typedef enum HintKeyword
        HINT_KEYWORD_NOHASHJOIN,
        HINT_KEYWORD_LEADING,
        HINT_KEYWORD_SET,
+       HINT_KEYWORD_ROWS,
        HINT_KEYWORD_UNRECOGNIZED
 } HintKeyword;
 
@@ -161,20 +162,22 @@ typedef const char *(*HintParseFunction) (Hint *hint, HintState *hstate,
                                                                                  Query *parse, const char *str);
 
 /* hint types */
-#define NUM_HINT_TYPE  4
+#define NUM_HINT_TYPE  5
 typedef enum HintType
 {
        HINT_TYPE_SCAN_METHOD,
        HINT_TYPE_JOIN_METHOD,
        HINT_TYPE_LEADING,
-       HINT_TYPE_SET
+       HINT_TYPE_SET,
+       HINT_TYPE_ROWS,
 } HintType;
 
 static const char *HintTypeName[] = {
        "scan method",
        "join method",
        "leading",
-       "set"
+       "set",
+       "rows",
 };
 
 /* hint status */
@@ -261,6 +264,26 @@ 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;
+
 /*
  * Describes a context of hint processing.
  */
@@ -280,9 +303,8 @@ struct HintState
        ScanMethodHint **scan_hints;            /* parsed scan hints */
        int                             init_scan_mask;         /* initial value scan parameter */
        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_index_infos; /* infomation of inherit parent table's
+       List               *parent_index_infos; /* information of inherit parent table's
                                                                                 * index */
 
        /* for join method hints */
@@ -296,6 +318,9 @@ struct HintState
        /* for Set hints */
        SetHint           **set_hints;                  /* parsed Set hints */
        GucContext              context;                        /* which GUC parameters can we set? */
+
+       /* for Rows hints */
+       RowsHint          **rows_hints;                 /* parsed Rows hints */
 };
 
 /*
@@ -357,6 +382,15 @@ static void SetHintDesc(SetHint *hint, StringInfo buf);
 static int SetHintCmp(const SetHint *a, const SetHint *b);
 static const char *SetHintParse(SetHint *hint, HintState *hstate, Query *parse,
                                                                const char *str);
+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);
+static int RowsHintCmp(const RowsHint *a, const RowsHint *b);
+static const char *RowsHintParse(RowsHint *hint, HintState *hstate,
+                                                                Query *parse, const char *str);
+static Hint *LeadingHintCreate(const char *hint_str, const char *keyword,
+                                                          HintKeyword hint_keyword);
 
 static void quote_value(StringInfo buf, const char *value);
 
@@ -375,22 +409,27 @@ static void make_rels_by_clauseless_joins(PlannerInfo *root,
 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 Path *get_cheapest_parameterized_child_path(PlannerInfo *root,
+                                                                         RelOptInfo *rel,
+                                                                         Relids required_outer);
 static List *accumulate_append_subpath(List *subpaths, Path *path);
-#if PG_VERSION_NUM < 90200
-static void set_dummy_rel_pathlist(RelOptInfo *rel);
-#endif
 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);
+
 /* 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},
@@ -444,12 +483,10 @@ static const HintParser parsers[] = {
        {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},
@@ -458,17 +495,27 @@ static const HintParser parsers[] = {
        {HINT_NOHASHJOIN, JoinMethodHintCreate, HINT_KEYWORD_NOHASHJOIN},
        {HINT_LEADING, LeadingHintCreate, HINT_KEYWORD_LEADING},
        {HINT_SET, SetHintCreate, HINT_KEYWORD_SET},
+       {HINT_ROWS, RowsHintCreate, HINT_KEYWORD_ROWS},
        {NULL, NULL, HINT_KEYWORD_UNRECOGNIZED}
 };
 
-/* search hint. */
-static 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";
+/*
+ * PL/pgSQL plugin for retrieving string representation of each query during
+ * function execution.
+ */
+const char *plpgsql_query_string = NULL;
+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
@@ -476,6 +523,8 @@ static const char *search_query =
 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.",
@@ -511,6 +560,17 @@ _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;
@@ -520,6 +580,10 @@ _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;
 }
 
 /*
@@ -529,11 +593,17 @@ _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;
 }
 
 /*
@@ -694,6 +764,54 @@ 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 HintState *
 HintStateCreate(void)
 {
@@ -708,7 +826,6 @@ HintStateCreate(void)
        hstate->scan_hints = NULL;
        hstate->init_scan_mask = 0;
        hstate->parent_relid = 0;
-       hstate->parent_rel_oid = InvalidOid;
        hstate->parent_hint = NULL;
        hstate->parent_index_infos = NIL;
        hstate->join_hints = NULL;
@@ -717,6 +834,7 @@ HintStateCreate(void)
        hstate->leading_hint = NULL;
        hstate->context = superuser() ? PGC_SUSET : PGC_USERSET;
        hstate->set_hints = NULL;
+       hstate->rows_hints = NULL;
 
        return hstate;
 }
@@ -881,8 +999,28 @@ SetHintDesc(SetHint *hint, StringInfo buf)
        appendStringInfo(buf, ")\n");
 }
 
+static void
+RowsHintDesc(RowsHint *hint, StringInfo buf)
+{
+       int     i;
+
+       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]);
+               }
+       }
+       appendStringInfo(buf, " %s", hint->rows_str);
+       appendStringInfoString(buf, ")\n");
+
+}
+
 /*
- * 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
@@ -978,6 +1116,24 @@ SetHintCmp(const SetHint *a, const SetHint *b)
 }
 
 static int
+RowsHintCmp(const RowsHint *a, const RowsHint *b)
+{
+       int     i;
+
+       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
 HintCmp(const void *a, const void *b)
 {
        const Hint *hinta = *((const Hint **) a);
@@ -1243,9 +1399,7 @@ parse_parentheses(const char *str, List **name_list, HintKeyword keyword)
                skip_space(str);
 
                if (keyword == HINT_KEYWORD_INDEXSCANREGEXP ||
-#if PG_VERSION_NUM >= 90200
                        keyword == HINT_KEYWORD_INDEXONLYSCANREGEXP ||
-#endif
                        keyword == HINT_KEYWORD_BITMAPSCANREGEXP ||
                        keyword == HINT_KEYWORD_SET)
                {
@@ -1333,75 +1487,87 @@ parse_hints(HintState *hstate, Query *parse, const char *str)
 }
 
 
-/* search hint. */
-static bool
-search_hints(
-                        const char *query,
-                        const char *query_string,
-                        const char *app_name)
-{
+/* 
+ * 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;
-       int             ret;
-       char    buf[8192];
+       char   *hints = NULL;
        Oid             argtypes[2] = { TEXTOID, TEXTOID };
        Datum   values[2];
        bool    nulls[2] = { false, false };
-       text   *str;
+       text   *qry;
        text   *app;
 
-       ret = SPI_connect();
-       if (ret != SPI_OK_CONNECT)
-               elog(ERROR, "pg_hint_plan: SPI_connect => %d", ret);
-
-       if (plan == NULL)
+       PG_TRY();
        {
-               SPIPlanPtr      p;
-               p = SPI_prepare(query, 2, argtypes);
-               if (p == NULL)
-                       elog(ERROR, "pg_hint_plan: SPI_prepare => %d", SPI_result);
-               plan = SPI_saveplan(p);
-               SPI_freeplan(p);
+               ++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;
        }
-
-       str = cstring_to_text(query_string);
-       app = cstring_to_text(app_name);
-       values[0] = PointerGetDatum(str);
-       values[1] = PointerGetDatum(app);
-
-       pg_hint_plan_enable_hint = false;
-       ret = SPI_execute_plan(plan, values, nulls, true, 1);
-       pg_hint_plan_enable_hint = true;
-       if (ret != SPI_OK_SELECT)
-               elog(ERROR, "pg_hint_plan: SPI_execute_plan => %d", ret);
-
-       if (SPI_processed > 0)
+       PG_CATCH();
        {
-               sprintf(buf, "%s", SPI_getvalue(SPI_tuptable->vals[0], SPI_tuptable->tupdesc, 1));
-               elog(LOG, "pg_hint_plan: SPI_execute_plan vals => %s", buf);
+               --nested_level;
+               PG_RE_THROW();
        }
-       else
-               elog(LOG, "pg_hint_plan: SPI_execute_plan rows => 0");
-       
-       SPI_finish();
+       PG_END_TRY();
 
-       return SPI_processed > 0;
+       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;
-       const char *hint_head;
-       char       *head;
-       char       *tail;
-       int                     len;
-       int                     i;
-       HintState   *hstate;
 
-       /* get client-supplied query string. */
        if (stmt_name)
        {
                PreparedStatement  *entry;
@@ -1409,9 +1575,25 @@ 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;
 
@@ -1469,8 +1651,25 @@ 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);
@@ -1495,7 +1694,7 @@ 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++)
@@ -1533,6 +1732,8 @@ parse_head_comment(Query *parse)
                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]);
 
        return hstate;
 }
@@ -1563,10 +1764,8 @@ ScanMethodHintParse(ScanMethodHint *hint, HintState *hstate, Query *parse,
                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 &&
                        hint_keyword != HINT_KEYWORD_BITMAPSCANREGEXP)
                {
@@ -1621,7 +1820,6 @@ 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;
@@ -1632,7 +1830,6 @@ ScanMethodHintParse(ScanMethodHint *hint, HintState *hstate, Query *parse,
                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;
@@ -1828,6 +2025,97 @@ SetHintParse(SetHint *hint, HintState *hstate, Query *parse, const char *str)
        return str;
 }
 
+static const char *
+RowsHintParse(RowsHint *hint, HintState *hstate, Query *parse,
+                         const char *str)
+{
+       HintKeyword             hint_keyword = hint->base.hint_keyword;
+       List               *name_list = NIL;
+       char               *rows_str;
+       char               *end_ptr;
+
+       if ((str = parse_parentheses(str, &name_list, hint_keyword)) == NULL)
+               return NULL;
+
+       /* Last element must be rows specification */
+       hint->nrels = list_length(name_list) - 1;
+
+       if (hint->nrels > 0)
+       {
+               ListCell   *l;
+               int                     i = 0;
+
+               /*
+                * Transform relation names from list to array to sort them with qsort
+                * after.
+                */
+               hint->relnames = palloc(sizeof(char *) * hint->nrels);
+               foreach (l, name_list)
+               {
+                       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;
+}
+
 /*
  * set GUC parameter functions
  */
@@ -1842,13 +2130,8 @@ set_config_option_wrapper(const char *name, const char *value,
 
        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();
        {
@@ -1910,9 +2193,7 @@ set_scan_config_options(unsigned char enforce_mask, GucContext context)
 
        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
@@ -1922,9 +2203,7 @@ set_scan_config_options(unsigned char enforce_mask, GucContext context)
        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
@@ -1954,7 +2233,11 @@ 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,
@@ -1996,7 +2279,7 @@ pg_hint_plan_ProcessUtility(Node *parsetree, const char *queryString,
                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.
@@ -2017,7 +2300,7 @@ pg_hint_plan_ProcessUtility(Node *parsetree, const char *queryString,
                        stmt_name = estmt->name;
                }
        }
-#endif
+
        if (stmt_name)
        {
                PG_TRY();
@@ -2086,34 +2369,73 @@ 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();
 
        /*
-        *search hint.
-        * TODO: replace "app1" with current application_name setting of the
-        * session.
-        * XXX: use something instead of debug_query_string?
+        * 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.
         */
-       search_hints(search_query, debug_query_string, "app1");
-
-       /* Create hint struct from parse tree. */
-       hstate = parse_head_comment(parse);
+       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
@@ -2121,14 +2443,7 @@ 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.
@@ -2148,10 +2463,8 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
                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)
@@ -2194,6 +2507,13 @@ 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);
 }
 
 /*
@@ -2437,7 +2757,7 @@ delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
                                                }
                                        }
 
-                                       /* Check to match the predicate's paraameter of index */
+                                       /* Check to match the predicate's parameter of index */
                                        if (p_info->indpred_str &&
                                                !heap_attisnull(ht_idx, Anum_pg_index_indpred))
                                        {
@@ -2446,7 +2766,7 @@ delete_indexes(ScanMethodHint *hint, RelOptInfo *rel, Oid relationObjectId)
                                                Datum       result;
 
                                                /*
-                                                * to change the predicate's parabeter of child's
+                                                * to change the predicate's parameter of child's
                                                 * index to strings
                                                 */
                                                predDatum = SysCacheGetAttr(INDEXRELID, ht_idx,
@@ -2555,7 +2875,7 @@ get_parent_index_info(Oid indexoid, Oid relid)
        }
 
        /*
-        * to check to match the expression's paraameter of index with child indexes
+        * 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))
@@ -2575,7 +2895,7 @@ get_parent_index_info(Oid indexoid, Oid relid)
        }
 
        /*
-        * to check to match the predicate's paraameter of index with child indexes
+        * 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))
@@ -2608,15 +2928,17 @@ pg_hint_plan_get_relation_info(PlannerInfo *root, Oid relationObjectId,
        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 if (current_hint->parent_relid != 0)
        {
@@ -2645,7 +2967,6 @@ pg_hint_plan_get_relation_info(PlannerInfo *root, Oid relationObjectId,
 
                /* This rel is not inherit table. */
                current_hint->parent_relid = 0;
-               current_hint->parent_rel_oid = InvalidOid;
                current_hint->parent_hint = NULL;
        }
 
@@ -2857,6 +3178,46 @@ OuterInnerJoinCreate(OuterInnerRels *outer_inner, LeadingHint *leading_hint,
        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.
  *
@@ -2884,43 +3245,33 @@ transform_join_hints(HintState *hstate, PlannerInfo *root, int nbaserel,
        for (i = 0; i < hstate->num_hints[HINT_TYPE_JOIN_METHOD]; i++)
        {
                JoinMethodHint *hint = hstate->join_hints[i];
-               int     j;
 
                if (!hint_state_enabled(hint) || hint->nrels > nbaserel)
                        continue;
 
-               bms_free(hint->joinrelids);
-               hint->joinrelids = NULL;
-               relid = 0;
-               for (j = 0; j < hint->nrels; j++)
-               {
-                       relname = hint->relnames[j];
+               hint->joinrelids = create_bms_of_relids(&(hint->base), root,
+                                                                        initial_rels, hint->nrels, hint->relnames);
 
-                       relid = find_relid_aliasname(root, relname, initial_rels,
-                                                                                hint->base.hint_str);
-
-                       if (relid == -1)
-                               hint->base.state = HINT_STATE_ERROR;
-
-                       if (relid <= 0)
-                               break;
+               if (hint->joinrelids == NULL || hint->base.state == HINT_STATE_ERROR)
+                       continue;
 
-                       if (bms_is_member(relid, hint->joinrelids))
-                       {
-                               hint_ereport(hint->base.hint_str,
-                                                        ("Relation name \"%s\" is duplicated.", relname));
-                               hint->base.state = HINT_STATE_ERROR;
-                               break;
-                       }
+               hstate->join_hint_level[hint->nrels] =
+                       lappend(hstate->join_hint_level[hint->nrels], hint);
+       }
 
-                       hint->joinrelids = bms_add_member(hint->joinrelids, relid);
-               }
+       /*
+        * 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 (relid <= 0 || hint->base.state == HINT_STATE_ERROR)
+               if (!hint_state_enabled(hint) || hint->nrels > nbaserel)
                        continue;
 
-               hstate->join_hint_level[hint->nrels] =
-                       lappend(hstate->join_hint_level[hint->nrels], hint);
+               hint->joinrelids = create_bms_of_relids(&(hint->base), root,
+                                                                        initial_rels, hint->nrels, hint->relnames);
        }
 
        /* Do nothing if no Leading hint was supplied. */
@@ -3084,7 +3435,6 @@ transform_join_hints(HintState *hstate, PlannerInfo *root, int nbaserel,
                                ListCell *next = NULL;
                                for(l = list_head(hstate->join_hint_level[i]); l; l = next)
                                {
-
                                        JoinMethodHint *hint = (JoinMethodHint *)lfirst(l);
 
                                        next = lnext(l);
@@ -3126,11 +3476,7 @@ static void
 set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
 {
        /* 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);
@@ -3262,6 +3608,7 @@ add_paths_to_joinrel_wrapper(PlannerInfo *root,
        }
 
        joinrelids = bms_union(outerrel->relids, innerrel->relids);
+
        join_hint = find_join_hint(joinrelids);
        bms_free(joinrelids);
 
@@ -3336,9 +3683,10 @@ 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);
@@ -3397,15 +3745,11 @@ static void
 set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
                                 Index rti, RangeTblEntry *rte)
 {
-#if PG_VERSION_NUM >= 90200
        if (IS_DUMMY_REL(rel))
        {
                /* 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);
@@ -3427,6 +3771,70 @@ 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;
+}
+
+/*
+ * 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 ((enum PLpgSQL_stmt_types) stmt->cmd_type == PLPGSQL_STMT_EXECSQL)
+               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
@@ -3436,3 +3844,5 @@ 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"