OSDN Git Service

Change copyright year to 2020.
[pghintplan/pg_hint_plan.git] / pg_hint_plan.c
index 26db50d..bce01ad 100644 (file)
@@ -3,7 +3,7 @@
  * pg_hint_plan.c
  *               hinting on how to execute a query for PostgreSQL
  *
- * Copyright (c) 2012-2017, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
+ * Copyright (c) 2012-2020, NIPPON TELEGRAPH AND TELEPHONE CORPORATION
  *
  *-------------------------------------------------------------------------
  */
@@ -91,12 +91,12 @@ PG_MODULE_MAGIC;
 
 #define HINT_ARRAY_DEFAULT_INITSIZE 8
 
-#define hint_ereport(str, detail) \
+#define hint_ereport(str, detail) hint_parse_ereport(str, detail)
+#define hint_parse_ereport(str, detail) \
        do { \
-               ereport(pg_hint_plan_message_level,             \
-                       (errmsg("pg_hint_plan%s: hint syntax error at or near \"%s\"", qnostr, (str)), \
+               ereport(pg_hint_plan_parse_message_level,               \
+                       (errmsg("pg_hint_plan: hint syntax error at or near \"%s\"", (str)), \
                         errdetail detail)); \
-               msgqno = qno; \
        } while(0)
 
 #define skip_space(str) \
@@ -224,6 +224,14 @@ static unsigned int msgqno = 0;
 static char qnostr[32];
 static const char *current_hint_str = NULL;
 
+/*
+ * However we usually take a hint stirng in post_parse_analyze_hook, we still
+ * need to do so in planner_hook when client starts query execution from the
+ * bind message on a prepared query. This variable prevent duplicate and
+ * sometimes harmful hint string retrieval.
+ */
+static bool current_hint_retrieved = false;
+
 /* common data for all hints. */
 struct Hint
 {
@@ -350,9 +358,10 @@ struct HintState
        int                             init_min_para_tablescan_size;
        /* min_parallel_index_scan_size*/
        int                             init_min_para_indexscan_size;
-       int                             init_paratup_cost;      /* parallel_tuple_cost */
-       int                             init_parasetup_cost;/* parallel_setup_cost */
+       double                  init_paratup_cost;      /* parallel_tuple_cost */
+       double                  init_parasetup_cost;/* parallel_setup_cost */
 
+       PlannerInfo        *current_root;               /* PlannerInfo for the followings */
        Index                   parent_relid;           /* inherit parent of table relid */
        ScanMethodHint *parent_scan_hint;       /* scan hint for the parent */
        ParallelHint   *parent_parallel_hint; /* parallel hint for the parent */
@@ -386,6 +395,11 @@ static void push_hint(HintState *hstate);
 static void pop_hint(void);
 
 static void pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query);
+static void pg_hint_plan_ProcessUtility(PlannedStmt *pstmt,
+                                       const char *queryString,
+                                       ProcessUtilityContext context,
+                                       ParamListInfo params, QueryEnvironment *queryEnv,
+                                       DestReceiver *dest, char *completionTag);
 static PlannedStmt *pg_hint_plan_planner(Query *parse, int cursorOptions,
                                                                                 ParamListInfo boundParams);
 static RelOptInfo *pg_hint_plan_join_search(PlannerInfo *root,
@@ -497,15 +511,19 @@ static void setup_scan_method_enforcement(ScanMethodHint *scanhint,
                                                                                  HintState *state);
 static int set_config_int32_option(const char *name, int32 value,
                                                                        GucContext context);
+static int set_config_double_option(const char *name, double value,
+                                                                       GucContext context);
 
 /* GUC variables */
 static bool    pg_hint_plan_enable_hint = true;
 static int debug_level = 0;
-static int     pg_hint_plan_message_level = INFO;
+static int     pg_hint_plan_parse_message_level = INFO;
+static int     pg_hint_plan_debug_message_level = LOG;
 /* Default is off, to keep backward compatibility. */
 static bool    pg_hint_plan_enable_hint_table = false;
 
 static int plpgsql_recurse_level = 0;          /* PLpgSQL recursion level            */
+static int recurse_level = 0;          /* recursion level incl. direct SPI calls */
 static int hint_inhibit_level = 0;                     /* Inhibit hinting if this is above 0 */
                                                                                        /* (This could not be above 1)        */
 static int max_hint_nworkers = -1;             /* Maximum nworkers of Workers hints */
@@ -550,6 +568,7 @@ static post_parse_analyze_hook_type prev_post_parse_analyze_hook = NULL;
 static planner_hook_type prev_planner = NULL;
 static join_search_hook_type prev_join_search = NULL;
 static set_rel_pathlist_hook_type prev_set_rel_pathlist = NULL;
+static ProcessUtility_hook_type prev_ProcessUtility_hook = NULL;
 
 /* Hold reference to currently active hint */
 static HintState *current_hint_state = NULL;
@@ -561,12 +580,6 @@ static HintState *current_hint_state = NULL;
  */
 static List *HintStateStack = NIL;
 
-/*
- * Holds statement name during executing EXECUTE command.  NULL for other
- * statements.
- */
-static char       *stmt_name = NULL;
-
 static const HintParser parsers[] = {
        {HINT_SEQSCAN, ScanMethodHintCreate, HINT_KEYWORD_SEQSCAN},
        {HINT_INDEXSCAN, ScanMethodHintCreate, HINT_KEYWORD_INDEXSCAN},
@@ -644,7 +657,7 @@ _PG_init(void)
        DefineCustomEnumVariable("pg_hint_plan.parse_messages",
                                                         "Message level of parse errors.",
                                                         NULL,
-                                                        &pg_hint_plan_message_level,
+                                                        &pg_hint_plan_parse_message_level,
                                                         INFO,
                                                         parse_messages_level_options,
                                                         PGC_USERSET,
@@ -656,8 +669,8 @@ _PG_init(void)
        DefineCustomEnumVariable("pg_hint_plan.message_level",
                                                         "Message level of debug messages.",
                                                         NULL,
-                                                        &pg_hint_plan_message_level,
-                                                        INFO,
+                                                        &pg_hint_plan_debug_message_level,
+                                                        LOG,
                                                         parse_messages_level_options,
                                                         PGC_USERSET,
                                                         0,
@@ -685,6 +698,8 @@ _PG_init(void)
        join_search_hook = pg_hint_plan_join_search;
        prev_set_rel_pathlist = set_rel_pathlist_hook;
        set_rel_pathlist_hook = pg_hint_plan_set_rel_pathlist;
+       prev_ProcessUtility_hook = ProcessUtility_hook;
+       ProcessUtility_hook = pg_hint_plan_ProcessUtility;
 
        /* setup PL/pgSQL plugin hook */
        var_ptr = (PLpgSQL_plugin **) find_rendezvous_variable("PLpgSQL_plugin");
@@ -707,6 +722,7 @@ _PG_fini(void)
        planner_hook = prev_planner;
        join_search_hook = prev_join_search;
        set_rel_pathlist_hook = prev_set_rel_pathlist;
+       ProcessUtility_hook = prev_ProcessUtility_hook;
 
        /* uninstall PL/pgSQL plugin hook */
        var_ptr = (PLpgSQL_plugin **) find_rendezvous_variable("PLpgSQL_plugin");
@@ -925,7 +941,7 @@ ParallelHintCreate(const char *hint_str, const char *keyword,
 {
        ParallelHint *hint;
 
-       hint = palloc(sizeof(ScanMethodHint));
+       hint = palloc(sizeof(ParallelHint));
        hint->base.hint_str = hint_str;
        hint->base.keyword = keyword;
        hint->base.hint_keyword = hint_keyword;
@@ -972,6 +988,7 @@ HintStateCreate(void)
        hstate->init_min_para_indexscan_size = 0;
        hstate->init_paratup_cost = 0;
        hstate->init_parasetup_cost = 0;
+       hstate->current_root = NULL;
        hstate->parent_relid = 0;
        hstate->parent_scan_hint = NULL;
        hstate->parent_parallel_hint = NULL;
@@ -1170,7 +1187,8 @@ RowsHintDesc(RowsHint *hint, StringInfo buf, bool nolf)
                        quote_value(buf, hint->relnames[i]);
                }
        }
-       appendStringInfo(buf, " %s", hint->rows_str);
+       if (hint->rows_str != NULL)
+               appendStringInfo(buf, " %s", hint->rows_str);
        appendStringInfoString(buf, ")");
        if (!nolf)
                appendStringInfoChar(buf, '\n');
@@ -1235,7 +1253,7 @@ HintStateDump(HintState *hstate)
 
        if (!hstate)
        {
-               elog(LOG, "pg_hint_plan:\nno hint");
+               elog(pg_hint_plan_debug_message_level, "pg_hint_plan:\nno hint");
                return;
        }
 
@@ -1247,7 +1265,8 @@ HintStateDump(HintState *hstate)
        desc_hint_in_state(hstate, &buf, "duplication hint", HINT_STATE_DUPLICATION, false);
        desc_hint_in_state(hstate, &buf, "error hint", HINT_STATE_ERROR, false);
 
-       elog(LOG, "%s", buf.data);
+       ereport(pg_hint_plan_debug_message_level,
+                       (errmsg ("%s", buf.data)));
 
        pfree(buf.data);
 }
@@ -1259,7 +1278,7 @@ HintStateDump2(HintState *hstate)
 
        if (!hstate)
        {
-               elog(pg_hint_plan_message_level,
+               elog(pg_hint_plan_debug_message_level,
                         "pg_hint_plan%s: HintStateDump: no hint", qnostr);
                return;
        }
@@ -1272,7 +1291,7 @@ HintStateDump2(HintState *hstate)
        desc_hint_in_state(hstate, &buf, "}, {error hints", HINT_STATE_ERROR, true);
        appendStringInfoChar(&buf, '}');
 
-       ereport(pg_hint_plan_message_level,
+       ereport(pg_hint_plan_debug_message_level,
                        (errmsg("%s", buf.data),
                         errhidestmt(true),
                         errhidecontext(true)));
@@ -1655,7 +1674,7 @@ parse_hints(HintState *hstate, Query *parse, const char *str)
                        char   *keyword = parser->keyword;
                        Hint   *hint;
 
-                       if (strcasecmp(buf.data, keyword) != 0)
+                       if (pg_strcasecmp(buf.data, keyword) != 0)
                                continue;
 
                        hint = parser->create_func(head, keyword, parser->hint_keyword);
@@ -1794,26 +1813,46 @@ get_hints_from_table(const char *client_query, const char *client_application)
 /*
  * Get client-supplied query string. Addtion to that the jumbled query is
  * supplied if the caller requested. From the restriction of JumbleQuery, some
- * kind of query needs special amendments. Reutrns NULL if the current hint
- * string is still valid.
+ * kind of query needs special amendments. Reutrns NULL if this query doesn't
+ * change the current hint. This function returns NULL also when something
+ * wrong has happend and let the caller continue using the current hints.
  */
 static const char *
 get_query_string(ParseState *pstate, Query *query, Query **jumblequery)
 {
        const char *p = debug_query_string;
 
+       /*
+        * If debug_query_string is set, it is the top level statement. But in some
+        * cases we reach here with debug_query_string set NULL for example in the
+        * case of DESCRIBE message handling or EXECUTE command. We may still see a
+        * candidate top-level query in pstate in the case.
+        */
+       if (pstate && pstate->p_sourcetext)
+               p = pstate->p_sourcetext;
+
+       /* We don't see a query string, return NULL */
+       if (!p)
+               return NULL;
+
        if (jumblequery != NULL)
                *jumblequery = query;
 
        if (query->commandType == CMD_UTILITY)
        {
-               Query *target_query = query;
+               Query *target_query = (Query *)query->utilityStmt;
 
-               /* Use the target query if EXPLAIN */
-               if (IsA(query->utilityStmt, ExplainStmt))
+               /*
+                * Some CMD_UTILITY statements have a subquery that we can hint on.
+                * Since EXPLAIN can be placed before other kind of utility statements
+                * and EXECUTE can be contained other kind of utility statements, these
+                * conditions are not mutually exclusive and should be considered in
+                * this order.
+                */
+               if (IsA(target_query, ExplainStmt))
                {
-                       ExplainStmt *stmt = (ExplainStmt *)(query->utilityStmt);
-
+                       ExplainStmt *stmt = (ExplainStmt *)target_query;
+                       
                        Assert(IsA(stmt->query, Query));
                        target_query = (Query *)stmt->query;
 
@@ -1823,53 +1862,68 @@ get_query_string(ParseState *pstate, Query *query, Query **jumblequery)
                                target_query = (Query *)target_query->utilityStmt;
                }
 
+               if (IsA(target_query, DeclareCursorStmt))
+               {
+                       DeclareCursorStmt *stmt = (DeclareCursorStmt *)target_query;
+                       Query *query = (Query *)stmt->query;
+
+                       /* the target must be CMD_SELECT in this case */
+                       Assert(IsA(query, Query) && query->commandType == CMD_SELECT);
+                       target_query = query;
+               }
+
                if (IsA(target_query, CreateTableAsStmt))
                {
-                       /*
-                        * Use the the body query for CREATE AS. The Query for jumble also
-                        * replaced with the corresponding one.
-                        */
                        CreateTableAsStmt  *stmt = (CreateTableAsStmt *) target_query;
-                       PreparedStatement  *entry;
-                       Query                      *tmp_query;
 
                        Assert(IsA(stmt->query, Query));
-                       tmp_query = (Query *) stmt->query;
+                       target_query = (Query *) stmt->query;
 
-                       if (tmp_query->commandType == CMD_UTILITY &&
-                               IsA(tmp_query->utilityStmt, ExecuteStmt))
-                       {
-                               ExecuteStmt *estmt = (ExecuteStmt *) tmp_query->utilityStmt;
-                               entry = FetchPreparedStatement(estmt->name, true);
-                               p = entry->plansource->query_string;
-                               target_query = (Query *) linitial (entry->plansource->query_list);
-                       }
+                       /* strip out the top-level query for further processing */
+                       if (target_query->commandType == CMD_UTILITY &&
+                               target_query->utilityStmt != NULL)
+                               target_query = (Query *)target_query->utilityStmt;
                }
-               else
+
                if (IsA(target_query, ExecuteStmt))
                {
                        /*
-                        * Use the prepared query for EXECUTE. The Query for jumble also
-                        * replaced with the corresponding one.
+                        * Use the prepared query for EXECUTE. The Query for jumble
+                        * also replaced with the corresponding one.
                         */
                        ExecuteStmt *stmt = (ExecuteStmt *)target_query;
                        PreparedStatement  *entry;
 
                        entry = FetchPreparedStatement(stmt->name, true);
-                       p = entry->plansource->query_string;
-                       target_query = (Query *) linitial (entry->plansource->query_list);
-               }
 
-               /* We don't accept other than a Query other than a CMD_UTILITY */
-               if (!IsA(target_query, Query) ||
-                       target_query->commandType == CMD_UTILITY)
+                       if (entry->plansource->is_valid)
+                       {
+                               p = entry->plansource->query_string;
+                               target_query = (Query *) linitial (entry->plansource->query_list);
+                       }
+                       else
+                       {
+                               /* igonre the hint for EXECUTE if invalidated */
+                               p = NULL;
+                               target_query = NULL;
+                       }
+               }
+                       
+               /* JumbleQuery accespts only a non-utility Query */
+               if (target_query &&
+                       (!IsA(target_query, Query) ||
+                        target_query->utilityStmt != NULL))
                        target_query = NULL;
 
                if (jumblequery)
                        *jumblequery = target_query;
        }
-       /* Return NULL if the pstate is not identical to the top-level query */
-       else if (strcmp(pstate->p_sourcetext, p) != 0)
+       /*
+        * Return NULL if pstate is not of top-level query.  We don't need this
+        * when jumble info is not requested or cannot do this when pstate is NULL.
+        */
+       else if (!jumblequery && pstate && pstate->p_sourcetext != p &&
+                        strcmp(pstate->p_sourcetext, p) != 0)
                p = NULL;
 
        return p;
@@ -2323,6 +2377,8 @@ RowsHintParse(RowsHint *hint, HintState *hstate, Query *parse,
        List               *name_list = NIL;
        char               *rows_str;
        char               *end_ptr;
+       ListCell   *l;
+       int                     i = 0;
 
        if ((str = parse_parentheses(str, &name_list, hint_keyword)) == NULL)
                return NULL;
@@ -2330,23 +2386,28 @@ RowsHintParse(RowsHint *hint, HintState *hstate, Query *parse,
        /* Last element must be rows specification */
        hint->nrels = list_length(name_list) - 1;
 
-       if (hint->nrels > 0)
+       if (hint->nrels < 1)
        {
-               ListCell   *l;
-               int                     i = 0;
+               hint_ereport(str,
+                                        ("%s hint needs at least one relation followed by one correction term.",
+                                         hint->base.keyword));
+               hint->base.state = HINT_STATE_ERROR;
 
-               /*
-                * 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++;
-               }
+               return str;
+       }
+       
+
+       /*
+        * 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 */
@@ -2461,9 +2522,9 @@ ParallelHintParse(ParallelHint *hint, HintState *hstate, Query *parse,
        if (length == 3)
        {
                const char *modeparam = (const char *)list_nth(name_list, 2);
-               if (strcasecmp(modeparam, "hard") == 0)
+               if (pg_strcasecmp(modeparam, "hard") == 0)
                        force_parallel = true;
-               else if (strcasecmp(modeparam, "soft") != 0)
+               else if (pg_strcasecmp(modeparam, "soft") != 0)
                {
                        hint_ereport(modeparam,
                                                 ("enforcement must be soft or hard: %s",
@@ -2569,16 +2630,32 @@ set_config_int32_option(const char *name, int32 value, GucContext context)
 
        if (snprintf(buf, 16, "%d", value) < 0)
        {
-               ereport(pg_hint_plan_message_level,
-                               (errmsg ("Cannot set integer value: %d: %s",
-                                                max_hint_nworkers, strerror(errno))));
+               ereport(pg_hint_plan_parse_message_level,
+                               (errmsg ("Failed to convert integer to string: %d", value)));
                return false;
        }
 
        return
                set_config_option_noerror(name, buf, context,
                                                                  PGC_S_SESSION, GUC_ACTION_SAVE, true,
-                                                                 pg_hint_plan_message_level);
+                                                                 pg_hint_plan_parse_message_level);
+}
+
+/*
+ * Sets GUC parameter of double type without throwing exceptions. Returns false
+ * if something wrong.
+ */
+static int
+set_config_double_option(const char *name, double value, GucContext context)
+{
+       char *buf = float8out_internal(value);
+       int       result;
+
+       result = set_config_option_noerror(name, buf, context,
+                                                                          PGC_S_SESSION, GUC_ACTION_SAVE, true,
+                                                                          pg_hint_plan_parse_message_level);
+       pfree(buf);
+       return result;
 }
 
 /* setup scan method enforcement according to given options */
@@ -2597,7 +2674,7 @@ setup_guc_enforcement(SetHint **options, int noptions, GucContext context)
 
                result = set_config_option_noerror(hint->name, hint->value, context,
                                                                                   PGC_S_SESSION, GUC_ACTION_SAVE, true,
-                                                                                  pg_hint_plan_message_level);
+                                                                                  pg_hint_plan_parse_message_level);
                if (result != 0)
                        hint->base.state = HINT_STATE_USED;
                else
@@ -2628,8 +2705,8 @@ setup_parallel_plan_enforcement(ParallelHint *hint, HintState *state)
        /* force means that enforce parallel as far as possible */
        if (hint && hint->force_parallel)
        {
-               set_config_int32_option("parallel_tuple_cost", 0, state->context);
-               set_config_int32_option("parallel_setup_cost", 0, state->context);
+               set_config_double_option("parallel_tuple_cost", 0.0, state->context);
+               set_config_double_option("parallel_setup_cost", 0.0, state->context);
                set_config_int32_option("min_parallel_table_scan_size", 0,
                                                                state->context);
                set_config_int32_option("min_parallel_index_scan_size", 0,
@@ -2637,9 +2714,9 @@ setup_parallel_plan_enforcement(ParallelHint *hint, HintState *state)
        }
        else
        {
-               set_config_int32_option("parallel_tuple_cost",
+               set_config_double_option("parallel_tuple_cost",
                                                                state->init_paratup_cost, state->context);
-               set_config_int32_option("parallel_setup_cost",
+               set_config_double_option("parallel_setup_cost",
                                                                state->init_parasetup_cost, state->context);
                set_config_int32_option("min_parallel_table_scan_size",
                                                                state->init_min_para_tablescan_size,
@@ -2739,24 +2816,25 @@ pop_hint(void)
 }
 
 /*
- * Retrieve and store a hint string from given query or from the hint table.
- * If we are using the hint table, the query string is needed to be normalized.
- * However, ParseState, which is not available in planner_hook, is required to
- * check if the query tree (Query) is surely corresponding to the target query.
+ * Retrieve and store hint string from given query or from the hint table.
  */
 static void
-pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
+get_current_hint_string(ParseState *pstate, Query *query)
 {
        const char *query_str;
        MemoryContext   oldcontext;
 
-       if (prev_post_parse_analyze_hook)
-               prev_post_parse_analyze_hook(pstate, query);
-
        /* do nothing under hint table search */
        if (hint_inhibit_level > 0)
                return;
 
+       /* We alredy have one, don't parse it again. */
+       if (current_hint_retrieved)
+               return;
+
+       /* Don't parse the current query hereafter */
+       current_hint_retrieved = true;
+
        if (!pg_hint_plan_enable_hint)
        {
                if (current_hint_str)
@@ -2797,8 +2875,8 @@ pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
                if (jumblequery)
                {
                        /*
-                        * XXX: normalizing code is copied from pg_stat_statements.c, so be
-                        * careful to PostgreSQL's version up.
+                        * XXX: normalization code is copied from pg_stat_statements.c.
+                        * Make sure to keep up-to-date with it.
                         */
                        jstate.jumble = (unsigned char *) palloc(JUMBLE_SIZE);
                        jstate.jumble_len = 0;
@@ -2822,8 +2900,7 @@ pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
                         */
                        query_len = strlen(query_str) + 1;
                        normalized_query =
-                               generate_normalized_query(&jstate, query_str,
-                                                                                 &query_len,
+                               generate_normalized_query(&jstate, query_str, 0, &query_len,
                                                                                  GetDatabaseEncoding());
 
                        /*
@@ -2838,7 +2915,7 @@ pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
                        if (debug_level > 1)
                        {
                                if (current_hint_str)
-                                       ereport(pg_hint_plan_message_level,
+                                       ereport(pg_hint_plan_debug_message_level,
                                                        (errmsg("pg_hint_plan[qno=0x%x]: "
                                                                        "post_parse_analyze_hook: "
                                                                        "hints from table: \"%s\": "
@@ -2849,7 +2926,7 @@ pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
                                                         errhidestmt(msgqno != qno),
                                                         errhidecontext(msgqno != qno)));
                                else
-                                       ereport(pg_hint_plan_message_level,
+                                       ereport(pg_hint_plan_debug_message_level,
                                                        (errmsg("pg_hint_plan[qno=0x%x]: "
                                                                        "no match found in table:  "
                                                                        "application name = \"%s\", "
@@ -2863,7 +2940,7 @@ pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
                        }
                }
 
-               /* retrun if we have hint here*/
+               /* retrun if we have hint here */
                if (current_hint_str)
                        return;
        }
@@ -2874,8 +2951,8 @@ pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
        {
                /*
                 * get hints from the comment. However we may have the same query
-                * string with the previous call, but just retrieving hints is expected
-                * to be faster than checking for identicalness before retrieval.
+                * string with the previous call, but the extra comparison seems no
+                * use..
                 */
                if (current_hint_str)
                        pfree((void *)current_hint_str);
@@ -2884,21 +2961,30 @@ pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
                current_hint_str = get_hints_from_comment(query_str);
                MemoryContextSwitchTo(oldcontext);
        }
+       else
+       {
+               /*
+                * Failed to get query. We would be in fetching invalidated
+                * plancache. Try the next chance.
+                */
+               current_hint_retrieved = false;
+       }
 
        if (debug_level > 1)
        {
-               if (debug_level == 1 &&
-                       (stmt_name || strcmp(query_str, debug_query_string)))
-                       ereport(pg_hint_plan_message_level,
+               if (debug_level == 1 && query_str && debug_query_string &&
+                       strcmp(query_str, debug_query_string))
+                       ereport(pg_hint_plan_debug_message_level,
                                        (errmsg("hints in comment=\"%s\"",
                                                        current_hint_str ? current_hint_str : "(none)"),
                                         errhidestmt(msgqno != qno),
                                         errhidecontext(msgqno != qno)));
                else
-                       ereport(pg_hint_plan_message_level,
-                                       (errmsg("hints in comment=\"%s\", stmt=\"%s\", query=\"%s\", debug_query_string=\"%s\"",
+                       ereport(pg_hint_plan_debug_message_level,
+                                       (errmsg("hints in comment=\"%s\", query=\"%s\", debug_query_string=\"%s\"",
                                                        current_hint_str ? current_hint_str : "(none)",
-                                                       stmt_name, query_str, debug_query_string),
+                                                       query_str ? query_str : "(none)",
+                                                       debug_query_string ? debug_query_string : "(none)"),
                                         errhidestmt(msgqno != qno),
                                         errhidecontext(msgqno != qno)));
                msgqno = qno;
@@ -2906,6 +2992,44 @@ pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
 }
 
 /*
+ * Retrieve hint string from the current query.
+ */
+static void
+pg_hint_plan_post_parse_analyze(ParseState *pstate, Query *query)
+{
+       if (prev_post_parse_analyze_hook)
+               prev_post_parse_analyze_hook(pstate, query);
+
+       /* always retrieve hint from the top-level query string */
+       if (plpgsql_recurse_level == 0)
+               current_hint_retrieved = false;
+
+       get_current_hint_string(pstate, query);
+}
+
+/*
+ * We need to reset current_hint_retrieved flag always when a command execution
+ * is finished. This is true even for a pure utility command that doesn't
+ * involve planning phase.
+ */
+static void
+pg_hint_plan_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
+                                       ProcessUtilityContext context,
+                                       ParamListInfo params, QueryEnvironment *queryEnv,
+                                       DestReceiver *dest, char *completionTag)
+{
+       if (prev_ProcessUtility_hook)
+               prev_ProcessUtility_hook(pstmt, queryString, context, params, queryEnv,
+                                                                dest, completionTag);
+       else
+               standard_ProcessUtility(pstmt, queryString, context, params, queryEnv,
+                                                                dest, completionTag);
+
+       if (plpgsql_recurse_level == 0)
+               current_hint_retrieved = false;
+}
+
+/*
  * Read and set up hint information
  */
 static PlannedStmt *
@@ -2914,6 +3038,7 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
        int                             save_nestlevel;
        PlannedStmt        *result;
        HintState          *hstate;
+       const char         *prev_hint_str = NULL;
 
        /*
         * Use standard planner if pg_hint_plan is disabled or current nesting 
@@ -2923,7 +3048,7 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
        if (!pg_hint_plan_enable_hint || hint_inhibit_level > 0)
        {
                if (debug_level > 1)
-                       ereport(pg_hint_plan_message_level,
+                       ereport(pg_hint_plan_debug_message_level,
                                        (errmsg ("pg_hint_plan%s: planner: enable_hint=%d,"
                                                         " hint_inhibit_level=%d",
                                                         qnostr, pg_hint_plan_enable_hint,
@@ -2938,19 +3063,25 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
         * Support for nested plpgsql functions. This is quite ugly but this is the
         * only point I could find where I can get the query string.
         */
-       if (plpgsql_recurse_level > 0)
+       if (plpgsql_recurse_level > 0 &&
+               error_context_stack && error_context_stack->arg)
        {
                MemoryContext oldcontext;
 
-               if (current_hint_str)
-                       pfree((void *)current_hint_str);
-
                oldcontext = MemoryContextSwitchTo(TopMemoryContext);
                current_hint_str =
                        get_hints_from_comment((char *)error_context_stack->arg);
                MemoryContextSwitchTo(oldcontext);
        }
 
+       /*
+        * Query execution in extended protocol can be started without the analyze
+        * phase. In the case retrieve hint string here.
+        */
+       if (!current_hint_str)
+               get_current_hint_string(NULL, parse);
+
+       /* No hint, go the normal way */
        if (!current_hint_str)
                goto standard_planner_proc;
 
@@ -2994,13 +3125,22 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 
        if (debug_level > 1)
        {
-               ereport(pg_hint_plan_message_level,
+               ereport(pg_hint_plan_debug_message_level,
                                (errhidestmt(msgqno != qno),
                                 errmsg("pg_hint_plan%s: planner", qnostr))); 
                msgqno = qno;
        }
 
        /*
+        * The planner call below may replace current_hint_str. Store and restore
+        * it so that the subsequent planning in the upper level doesn't get
+        * confused.
+        */
+       recurse_level++;
+       prev_hint_str = current_hint_str;
+       current_hint_str = NULL;
+       
+       /*
         * Use PG_TRY mechanism to recover GUC parameters and current_hint_state to
         * the state when this planner started when error occurred in planner.
         */
@@ -3010,6 +3150,9 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
                        result = (*prev_planner) (parse, cursorOptions, boundParams);
                else
                        result = standard_planner(parse, cursorOptions, boundParams);
+
+               current_hint_str = prev_hint_str;
+               recurse_level--;
        }
        PG_CATCH();
        {
@@ -3017,12 +3160,25 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
                 * Rollback changes of GUC parameters, and pop current hint context
                 * from hint stack to rewind the state.
                 */
+               current_hint_str = prev_hint_str;
+               recurse_level--;
                AtEOXact_GUC(true, save_nestlevel);
                pop_hint();
                PG_RE_THROW();
        }
        PG_END_TRY();
 
+
+       /*
+        * current_hint_str is useless after planning of the top-level query.
+        */
+       if (recurse_level < 1 && current_hint_str)
+       {
+               pfree((void *)current_hint_str);
+               current_hint_str = NULL;
+               current_hint_retrieved = false;
+       }
+
        /* Print hint in debug mode. */
        if (debug_level == 1)
                HintStateDump(current_hint_state);
@@ -3041,7 +3197,7 @@ pg_hint_plan_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 standard_planner_proc:
        if (debug_level > 1)
        {
-               ereport(pg_hint_plan_message_level,
+               ereport(pg_hint_plan_debug_message_level,
                                (errhidestmt(msgqno != qno),
                                 errmsg("pg_hint_plan%s: planner: no valid hint",
                                                qnostr)));
@@ -3049,9 +3205,15 @@ standard_planner_proc:
        }
        current_hint_state = NULL;
        if (prev_planner)
-               return (*prev_planner) (parse, cursorOptions, boundParams);
+               result =  (*prev_planner) (parse, cursorOptions, boundParams);
        else
-               return standard_planner(parse, cursorOptions, boundParams);
+               result = standard_planner(parse, cursorOptions, boundParams);
+
+       /* The upper-level planner still needs the current hint state */
+       if (HintStateStack != NIL)
+               current_hint_state = (HintState *) lfirst(list_head(HintStateStack));
+
+       return result;
 }
 
 /*
@@ -3469,7 +3631,7 @@ restrict_indexes(PlannerInfo *root, ScanMethodHint *hint, RelOptInfo *rel,
                initStringInfo(&rel_buf);
                quote_value(&rel_buf, disprelname);
 
-               ereport(LOG,
+               ereport(pg_hint_plan_debug_message_level,
                                (errmsg("available indexes for %s(%s):%s",
                                         hint->base.keyword,
                                         rel_buf.data,
@@ -3599,7 +3761,7 @@ setup_hint_enforcement(PlannerInfo *root, RelOptInfo *rel,
        if (inhparent)
        {
                if (debug_level > 1)
-                       ereport(pg_hint_plan_message_level,
+                       ereport(pg_hint_plan_debug_message_level,
                                        (errhidestmt(true),
                                         errmsg ("pg_hint_plan%s: setup_hint_enforcement"
                                                         " skipping inh parent: relation=%u(%s), inhparent=%d,"
@@ -3610,6 +3772,10 @@ setup_hint_enforcement(PlannerInfo *root, RelOptInfo *rel,
                return 0;
        }
 
+       /* Forget about the parent of another subquery */
+       if (root != current_hint_state->current_root)
+               current_hint_state->parent_relid = 0;
+
        /* Find the parent for this relation other than the registered parent */
        foreach (l, root->append_rel_list)
        {
@@ -3618,7 +3784,10 @@ setup_hint_enforcement(PlannerInfo *root, RelOptInfo *rel,
                if (appinfo->child_relid == rel->relid)
                {
                        if (current_hint_state->parent_relid != appinfo->parent_relid)
+                       {
                                new_parent_relid = appinfo->parent_relid;
+                               current_hint_state->current_root = root;
+                       }
                        break;
                }
        }
@@ -3718,7 +3887,7 @@ setup_hint_enforcement(PlannerInfo *root, RelOptInfo *rel,
                        if (shint == current_hint_state->parent_scan_hint)
                                additional_message = " by parent hint";
 
-                       ereport(pg_hint_plan_message_level,
+                       ereport(pg_hint_plan_debug_message_level,
                                        (errhidestmt(true),
                                         errmsg ("pg_hint_plan%s: setup_hint_enforcement"
                                                         " index deletion%s:"
@@ -3748,7 +3917,7 @@ setup_hint_enforcement(PlannerInfo *root, RelOptInfo *rel,
        if (!shint && ! phint)
        {
                if (debug_level > 1)
-                       ereport(pg_hint_plan_message_level,
+                       ereport(pg_hint_plan_debug_message_level,
                                        (errhidestmt (true),
                                         errmsg ("pg_hint_plan%s: setup_hint_enforcement"
                                                         " no hint applied:"
@@ -4433,50 +4602,20 @@ pg_hint_plan_set_rel_pathlist(PlannerInfo * root, RelOptInfo *rel,
                return;
 
        /* Here, we regenerate paths with the current hint restriction */
-
-       if (found_hints & HINT_BM_SCAN_METHOD)
+       if (found_hints & HINT_BM_SCAN_METHOD || found_hints & HINT_BM_PARALLEL)
        {
-               /*
-                * With scan hints, we regenerate paths for this relation from the
-                * first under the restricion.
-                */
+               /* Just discard all the paths considered so far */
                list_free_deep(rel->pathlist);
                rel->pathlist = NIL;
 
-               set_plain_rel_pathlist(root, rel, rte);
-       }
-
-       if (found_hints & HINT_BM_PARALLEL)
-       {
-               Assert (phint);
-
-               /* the partial_pathlist may be for different parameters, discard it */
-               if (rel->partial_pathlist)
-               {
-                       list_free_deep(rel->partial_pathlist);
-                       rel->partial_pathlist = NIL;
-               }
-
-               /* also remove gather path */
-               if (rel->pathlist)
-               {
-                       ListCell *cell, *prev = NULL, *next;
+               list_free_deep(rel->partial_pathlist);
+               rel->partial_pathlist = NIL;
 
-                       for (cell = list_head(rel->pathlist) ; cell; cell = next)
-                       {
-                               Path *path = (Path *) lfirst(cell);
-
-                               next = lnext(cell);
-                               if (IsA(path, GatherPath))
-                                       rel->pathlist = list_delete_cell(rel->pathlist,
-                                                                                                        cell, prev);
-                               else
-                                       prev = cell;
-                       }
-               }
+               /* Regenerate paths with the current enforcement */
+               set_plain_rel_pathlist(root, rel, rte);
 
-               /* then generate new paths if needed */
-               if (phint->nworkers > 0)
+               /* Additional work to enforce parallel query execution */
+               if (phint && phint->nworkers > 0)
                {
                        /* Lower the priorities of non-parallel paths */
                        foreach (l, rel->pathlist)
@@ -4490,15 +4629,6 @@ pg_hint_plan_set_rel_pathlist(PlannerInfo * root, RelOptInfo *rel,
                                }
                        }
 
-                       /*
-                        * generate partial paths with enforcement, this is affected by
-                        * scan method enforcement. Specifically, the cost of this partial
-                        * seqscan path will be disabled_cost if seqscan is inhibited by
-                        * hint or GUC parameters.
-                        */
-                       Assert (rel->partial_pathlist == NIL);
-                       create_plain_partial_paths(root, rel);
-
                        /* enforce number of workers if requested */
                        if (phint->force_parallel)
                        {
@@ -4601,7 +4731,7 @@ void plpgsql_query_erase_callback(ResourceReleasePhase phase,
                                                                  bool isTopLevel,
                                                                  void *arg)
 {
-       if (phase != RESOURCE_RELEASE_AFTER_LOCKS)
+       if (!isTopLevel || phase != RESOURCE_RELEASE_AFTER_LOCKS)
                return;
        /* Cancel plpgsql nest level*/
        plpgsql_recurse_level = 0;