0001-Add-a-new-option-STATS-to-EXPLAIN-command-r3.patch

From 82ba847cdbd1074b8f630827b20eedefc6a451b9 Mon Sep 17 00:00:00 2001
From: Tatsuro Yamada <yamatattsu@gmail.com>
Date: Mon, 10 Feb 2025 08:33:23 +0900
Subject: [PATCH 1/3] Add a new option STATS to EXPLAIN command

This patch allows to show applied extended statistics in EXPLAIN command output.
It includes the following points:

- Rebased on 9926f854

- Added a new struct Applied_ExtStats in plannode.h (T4)
    - Hopefully this will solve the issue related to "-DCOPY_PARSE_PLAN_TREES"
      with cfbot.
    - To pass the extended statistics information from path to plan,
      it might be more appropriate to define a new structure in primnode.h
      rather than plannode.h. Any advice would be appreciated.

- Handled EXPLAIN(STATS, VERBOSE) option (M2)
    - Before the fix, schema name was always added to extended statistics name,
      but with this patch, schema name is added to the following only when
      VERBOSE option is selected:
        - Extended statistics name, table name, and column name

- Added Supported extended statistics types in document (M4)
---
 doc/src/sgml/ref/explain.sgml             |  14 +++
 src/backend/commands/explain.c            | 140 ++++++++++++++++++++++
 src/backend/nodes/makefuncs.c             |  11 ++
 src/backend/optimizer/plan/createplan.c   |  17 +++
 src/backend/optimizer/util/relnode.c      |  12 ++
 src/backend/optimizer/util/restrictinfo.c |  35 ++++++
 src/backend/statistics/extended_stats.c   |   8 ++
 src/backend/utils/adt/selfuncs.c          |  15 +++
 src/backend/utils/cache/lsyscache.c       |  49 ++++++++
 src/include/commands/explain.h            |   1 +
 src/include/nodes/makefuncs.h             |   2 +
 src/include/nodes/parsenodes.h            |   3 +
 src/include/nodes/pathnodes.h             |   5 +
 src/include/nodes/plannodes.h             |  15 +++
 src/include/optimizer/restrictinfo.h      |   2 +
 src/include/utils/lsyscache.h             |   3 +
 16 files changed, 332 insertions(+)

diff --git a/doc/src/sgml/ref/explain.sgml b/doc/src/sgml/ref/explain.sgml
index 6361a14e65d..176ff4b0f2f 100644
--- a/doc/src/sgml/ref/explain.sgml
+++ b/doc/src/sgml/ref/explain.sgml
@@ -43,6 +43,7 @@ EXPLAIN [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] <rep
     BUFFERS [ <replaceable class="parameter">boolean</replaceable> ]
     SERIALIZE [ { NONE | TEXT | BINARY } ]
     WAL [ <replaceable class="parameter">boolean</replaceable> ]
+    STATS [ <replaceable class="parameter">boolean</replaceable> ]
     TIMING [ <replaceable class="parameter">boolean</replaceable> ]
     SUMMARY [ <replaceable class="parameter">boolean</replaceable> ]
     MEMORY [ <replaceable class="parameter">boolean</replaceable> ]
@@ -250,6 +251,19 @@ ROLLBACK;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>STATS</literal></term>
+    <listitem>
+     <para>
+      Include information on applied <literal>Extended statistics</literal>.
+      Specifically, include the names of extended statistics and clauses.
+      Supported extended statistics types are Dependencies and MCV.
+      See <xref linkend="planner-stats-extended"/> for details about extended
+      statistics. This parameter defaults to <literal>FALSE</literal>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>TIMING</literal></term>
     <listitem>
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index c24e66f82e1..8aac5736864 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -94,6 +94,15 @@ static void show_qual(List *qual, const char *qlabel,
 static void show_scan_qual(List *qual, const char *qlabel,
 						   PlanState *planstate, List *ancestors,
 						   ExplainState *es);
+static char *deparse_stat_expression(Node *node,
+									 PlanState *planstate, List *ancestors,
+									 bool useprefix, ExplainState *es);
+static char *show_stat_qual(List *qual, int is_or,
+							PlanState *planstate, List *ancestors,
+							bool useprefix, ExplainState *es);
+static void show_scan_stats(List *stats, List *clauses, List *ors,
+							PlanState *planstate, List *ancestors,
+							ExplainState *es);
 static void show_upper_qual(List *qual, const char *qlabel,
 							PlanState *planstate, List *ancestors,
 							ExplainState *es);
@@ -223,6 +232,8 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
 			es->settings = defGetBoolean(opt);
 		else if (strcmp(opt->defname, "generic_plan") == 0)
 			es->generic = defGetBoolean(opt);
+		else if (strcmp(opt->defname, "stats") == 0)
+			es->stats = defGetBoolean(opt);
 		else if (strcmp(opt->defname, "timing") == 0)
 		{
 			timing_set = true;
@@ -497,6 +508,11 @@ standard_ExplainOneQuery(Query *query, int cursorOptions,
 
 	if (es->buffers)
 		bufusage_start = pgBufferUsage;
+
+	/* if this flag is true, applied ext stats are stored */
+	if (es->stats)
+		query->isExplain_Stats = true;
+
 	INSTR_TIME_SET_CURRENT(planstart);
 
 	/* plan the query */
@@ -2114,6 +2130,11 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (plan->qual)
 				show_instrumentation_count("Rows Removed by Filter", 1,
 										   planstate, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_IndexOnlyScan:
 			show_scan_qual(((IndexOnlyScan *) plan)->indexqual,
@@ -2130,10 +2151,20 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (es->analyze)
 				ExplainPropertyFloat("Heap Fetches", NULL,
 									 planstate->instrument->ntuples2, 0, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_BitmapIndexScan:
 			show_scan_qual(((BitmapIndexScan *) plan)->indexqualorig,
 						   "Index Cond", planstate, ancestors, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_BitmapHeapScan:
 			show_scan_qual(((BitmapHeapScan *) plan)->bitmapqualorig,
@@ -2164,6 +2195,12 @@ ExplainNode(PlanState *planstate, List *ancestors,
 										   planstate, es);
 			if (IsA(plan, CteScan))
 				show_ctescan_info(castNode(CteScanState, planstate), es);
+
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_Gather:
 			{
@@ -2231,6 +2268,11 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (plan->qual)
 				show_instrumentation_count("Rows Removed by Filter", 1,
 										   planstate, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_TableFuncScan:
 			if (es->verbose)
@@ -2345,6 +2387,11 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (plan->qual)
 				show_instrumentation_count("Rows Removed by Filter", 1,
 										   planstate, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_WindowAgg:
 			show_upper_qual(plan->qual, "Filter", planstate, ancestors, es);
@@ -2361,6 +2408,11 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (plan->qual)
 				show_instrumentation_count("Rows Removed by Filter", 1,
 										   planstate, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_Sort:
 			show_sort_keys(castNode(SortState, planstate), ancestors, es);
@@ -2687,6 +2739,94 @@ show_scan_qual(List *qual, const char *qlabel,
 	show_qual(qual, qlabel, planstate, ancestors, useprefix, es);
 }
 
+/*
+ * Show a generic expression
+ */
+static char *
+deparse_stat_expression(Node *node,
+						PlanState *planstate, List *ancestors,
+						bool useprefix, ExplainState *es)
+{
+	List	   *context;
+
+	/* Set up deparsing context */
+	context = set_deparse_context_plan(es->deparse_cxt,
+									   planstate->plan,
+									   ancestors);
+
+	/* Deparse the expression */
+	return deparse_expression(node, context, useprefix, false);
+}
+
+/*
+ * Show a qualifier expression for extended stats
+ */
+static char *
+show_stat_qual(List *qual, int is_or,
+			   PlanState *planstate, List *ancestors,
+			   bool useprefix, ExplainState *es)
+{
+	Node	   *node;
+
+	/* No work if empty qual */
+	if (qual == NIL)
+		return NULL;
+
+	/* Convert AND list to explicit AND */
+	switch (is_or)
+	{
+		case 0:
+			node = (Node *) make_ands_explicit(qual);
+			break;
+		case 1:
+			node = (Node *) make_ors_explicit(qual);
+			break;
+		case 2:
+			/* Extended stats for GROUP BY clause should be comma separeted string */
+			node = (Node *) qual;
+			break;
+		default:
+			elog(ERROR, "unexpected value: %d", is_or);
+			break;
+	}
+
+	/* And show it */
+	return deparse_stat_expression(node, planstate, ancestors, useprefix, es);
+}
+
+/*
+ * Show applied statistics for scan/agg/group plan node
+ */
+static void
+show_scan_stats(List *stats, List *clauses, List *ors,
+				PlanState *planstate, List *ancestors, ExplainState *es)
+{
+	ListCell   *lc1, *lc2, *lc3;
+	StringInfoData	str;
+	bool		useprefix;
+
+	useprefix = es->verbose;
+
+	forthree (lc1, stats, lc2, clauses, lc3, ors)
+	{
+		StatisticExtInfo   *stat = (StatisticExtInfo *) lfirst(lc1);
+		List   *applied_clauses = (List *) lfirst(lc2);
+		int		is_or = lfirst_int(lc3);
+
+		initStringInfo(&str);
+
+		if (useprefix)
+			appendStringInfo(&str, "%s.",
+							 get_namespace_name(get_statistics_namespace(stat->statOid)));
+
+		appendStringInfo(&str, "%s  Clauses: %s",
+						 get_statistics_name(stat->statOid),
+						 show_stat_qual(applied_clauses, is_or, planstate, ancestors, useprefix, es));
+
+		ExplainPropertyText("Ext Stats", str.data, es);
+	}
+}
+
 /*
  * Show a qualifier expression for an upper-level plan node
  */
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index 007612563ca..c09667a8b42 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -759,6 +759,17 @@ make_ands_explicit(List *andclauses)
 		return make_andclause(andclauses);
 }
 
+Expr *
+make_ors_explicit(List *orclauses)
+{
+	if (orclauses == NIL)
+		return (Expr *) makeBoolConst(true, false);
+	else if (list_length(orclauses) == 1)
+		return (Expr *) linitial(orclauses);
+	else
+		return make_orclause(orclauses);
+}
+
 List *
 make_ands_implicit(Expr *clause)
 {
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 816a2b2a576..7a92799700e 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -5455,6 +5455,8 @@ order_qual_clauses(PlannerInfo *root, List *clauses)
 static void
 copy_generic_path_info(Plan *dest, Path *src)
 {
+	ListCell *lc;
+
 	dest->disabled_nodes = src->disabled_nodes;
 	dest->startup_cost = src->startup_cost;
 	dest->total_cost = src->total_cost;
@@ -5462,6 +5464,21 @@ copy_generic_path_info(Plan *dest, Path *src)
 	dest->plan_width = src->pathtarget->width;
 	dest->parallel_aware = src->parallel_aware;
 	dest->parallel_safe = src->parallel_safe;
+
+	/* Is this the right place to use makeNode()? */
+	dest->app_extstats = makeNode(Applied_ExtStats);
+	dest->app_extstats->applied_stats = src->parent->applied_stats;
+	dest->app_extstats->applied_clauses_or = src->parent->applied_clauses_or;
+	dest->app_extstats->applied_clauses = NIL;
+
+	foreach (lc, src->parent->applied_clauses)
+	{
+		List *clauses = (List *) lfirst(lc);
+
+		dest->app_extstats->applied_clauses
+			= lappend(dest->app_extstats->applied_clauses,
+					  maybe_extract_actual_clauses(clauses, false));
+	}
 }
 
 /*
diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index ff507331a06..b46ad85cba4 100644
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -287,6 +287,10 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptInfo *parent)
 	rel->partexprs = NULL;
 	rel->nullable_partexprs = NULL;
 
+	rel->applied_stats = NIL;
+	rel->applied_clauses = NIL;
+	rel->applied_clauses_or = NIL;
+
 	/*
 	 * Pass assorted information down the inheritance hierarchy.
 	 */
@@ -769,6 +773,10 @@ build_join_rel(PlannerInfo *root,
 	joinrel->partexprs = NULL;
 	joinrel->nullable_partexprs = NULL;
 
+	joinrel->applied_stats = NIL;
+	joinrel->applied_clauses = NIL;
+	joinrel->applied_clauses_or = NIL;
+
 	/* Compute information relevant to the foreign relations. */
 	set_foreign_rel_properties(joinrel, outer_rel, inner_rel);
 
@@ -953,6 +961,10 @@ build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel,
 	joinrel->partexprs = NULL;
 	joinrel->nullable_partexprs = NULL;
 
+	joinrel->applied_stats = NIL;
+	joinrel->applied_clauses = NIL;
+	joinrel->applied_clauses_or = NIL;
+
 	/* Compute information relevant to foreign relations. */
 	set_foreign_rel_properties(joinrel, outer_rel, inner_rel);
 
diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c
index a80083d2323..b6cc5d7c2e2 100644
--- a/src/backend/optimizer/util/restrictinfo.c
+++ b/src/backend/optimizer/util/restrictinfo.c
@@ -499,6 +499,41 @@ extract_actual_clauses(List *restrictinfo_list,
 	return result;
 }
 
+/*
+ * maybe_extract_actual_clauses
+ *
+ * Just like extract_actual_clauses, but does not require the clauses to
+ * already be RestrictInfo.
+ *
+ * XXX Does not handle RestrictInfos nested in OR clauses.
+ */
+List *
+maybe_extract_actual_clauses(List *restrictinfo_list,
+							 bool pseudoconstant)
+{
+	List	   *result = NIL;
+	ListCell   *l;
+
+	foreach(l, restrictinfo_list)
+	{
+		RestrictInfo   *rinfo;
+		Node *node = (Node *) lfirst(l);
+
+		if (!IsA(node, RestrictInfo))
+		{
+			result = lappend(result, node);
+			continue;
+		}
+
+		rinfo = (RestrictInfo *) node;
+
+		if (rinfo->pseudoconstant == pseudoconstant)
+			result = lappend(result, rinfo->clause);
+	}
+
+	return result;
+}
+
 /*
  * extract_actual_join_clauses
  *
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index a8b63ec0884..c7367252aee 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -1854,6 +1854,14 @@ statext_mcv_clauselist_selectivity(PlannerInfo *root, List *clauses, int varReli
 			list_exprs[listidx] = NULL;
 		}
 
+		/* add it to the list of applied stats/clauses, if this flag is true */
+		if (root->parse->isExplain_Stats)
+		{
+			rel->applied_stats = lappend(rel->applied_stats, stat);
+			rel->applied_clauses = lappend(rel->applied_clauses, stat_clauses);
+			rel->applied_clauses_or = lappend_int(rel->applied_clauses_or, (is_or) ? 1 : 0);
+		}
+
 		if (is_or)
 		{
 			bool	   *or_matches = NULL;
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index d3d1e485bb2..3258a3517a3 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -4083,6 +4083,7 @@ estimate_multivariate_ndistinct(PlannerInfo *root, RelOptInfo *rel,
 		ListCell   *lc2;
 		Bitmapset  *matched = NULL;
 		AttrNumber	attnum_offset;
+		List	   *matched_exprs = NIL;
 
 		/*
 		 * How much we need to offset the attnums? If there are no
@@ -4130,6 +4131,9 @@ estimate_multivariate_ndistinct(PlannerInfo *root, RelOptInfo *rel,
 
 				matched = bms_add_member(matched, attnum);
 
+				/* track expressions matched by this statistics */
+				matched_exprs = lappend(matched_exprs, varinfo->var);
+
 				found = true;
 			}
 
@@ -4158,6 +4162,9 @@ estimate_multivariate_ndistinct(PlannerInfo *root, RelOptInfo *rel,
 
 					matched = bms_add_member(matched, attnum);
 
+					/* track expressions matched by this statistics */
+					matched_exprs = lappend(matched_exprs, expr);
+
 					/* there should be just one matching expression */
 					break;
 				}
@@ -4166,6 +4173,14 @@ estimate_multivariate_ndistinct(PlannerInfo *root, RelOptInfo *rel,
 			}
 		}
 
+		/* add it to the list of applied stats/clauses, if this flag is true */
+		if (root->parse->isExplain_Stats)
+		{
+			rel->applied_stats = lappend(rel->applied_stats, matched_info);
+			rel->applied_clauses = lappend(rel->applied_clauses, matched_exprs);
+			rel->applied_clauses_or = lappend_int(rel->applied_clauses_or, 2); /* 2: Use comma to deparse */
+		}
+
 		/* Find the specific item that exactly matches the combination */
 		for (i = 0; i < stats->nitems; i++)
 		{
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index bcfa5cb4add..36e3f72b041 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -36,6 +36,7 @@
 #include "catalog/pg_publication.h"
 #include "catalog/pg_range.h"
 #include "catalog/pg_statistic.h"
+#include "catalog/pg_statistic_ext.h"
 #include "catalog/pg_subscription.h"
 #include "catalog/pg_transform.h"
 #include "catalog/pg_type.h"
@@ -3741,3 +3742,51 @@ get_subscription_name(Oid subid, bool missing_ok)
 
 	return subname;
 }
+
+/*
+ * get_statistics_name
+ *		Returns the name of a given extended statistics
+ *
+ * Returns a palloc'd copy of the string, or NULL if no such name.
+ */
+char *
+get_statistics_name(Oid stxid)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(stxid));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_statistic_ext stxtup = (Form_pg_statistic_ext) GETSTRUCT(tp);
+		char	   *result;
+
+		result = pstrdup(NameStr(stxtup->stxname));
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return NULL;
+}
+
+/*
+ * get_statistics_namespace
+ *		Returns the namespace OID of a given extended statistics
+ */
+Oid
+get_statistics_namespace(Oid stxid)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache1(STATEXTOID, ObjectIdGetDatum(stxid));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_statistic_ext stxtup = (Form_pg_statistic_ext) GETSTRUCT(tp);
+		Oid		result;
+
+		result = stxtup->stxnamespace;
+		ReleaseSysCache(tp);
+		return result;
+	}
+	else
+		return InvalidOid;
+}
diff --git a/src/include/commands/explain.h b/src/include/commands/explain.h
index ea7419951f4..797075126a0 100644
--- a/src/include/commands/explain.h
+++ b/src/include/commands/explain.h
@@ -55,6 +55,7 @@ typedef struct ExplainState
 	bool		memory;			/* print planner's memory usage information */
 	bool		settings;		/* print modified settings */
 	bool		generic;		/* generate a generic plan */
+	bool		stats;			/* print applied extended stats */
 	ExplainSerializeOption serialize;	/* serialize the query's output? */
 	ExplainFormat format;		/* output format */
 	/* state for output formatting --- not reset for each new plan tree */
diff --git a/src/include/nodes/makefuncs.h b/src/include/nodes/makefuncs.h
index 5473ce9a288..b32aa762c9b 100644
--- a/src/include/nodes/makefuncs.h
+++ b/src/include/nodes/makefuncs.h
@@ -95,6 +95,8 @@ extern Node *make_and_qual(Node *qual1, Node *qual2);
 extern Expr *make_ands_explicit(List *andclauses);
 extern List *make_ands_implicit(Expr *clause);
 
+extern Expr *make_ors_explicit(List *orclauses);
+
 extern IndexInfo *makeIndexInfo(int numattrs, int numkeyattrs, Oid amoid,
 								List *expressions, List *predicates,
 								bool unique, bool nulls_not_distinct,
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 8dd421fa0ef..27b48629e66 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -249,6 +249,9 @@ typedef struct Query
 	ParseLoc	stmt_location;
 	/* length in bytes; 0 means "rest of string" */
 	ParseLoc	stmt_len pg_node_attr(query_jumble_ignore);
+
+	/* if true, query is explain with stats option */
+	bool        isExplain_Stats;
 } Query;
 
 
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 00c700cc3e7..569d876fdfe 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -1068,6 +1068,11 @@ typedef struct RelOptInfo
 	List	  **partexprs pg_node_attr(read_write_ignore);
 	/* Nullable partition key expressions */
 	List	  **nullable_partexprs pg_node_attr(read_write_ignore);
+
+	/* info about applied extended statistics */
+	List       *applied_stats;		/* list of StatisticExtInfo */
+	List       *applied_clauses;	/* list of lists of clauses */
+	List       *applied_clauses_or;	/* are the clauses AND, OR, or Comma */
 } RelOptInfo;
 
 /*
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 2a2cf816cb6..39d2d131348 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -177,6 +177,9 @@ typedef struct Plan
 	 */
 	Bitmapset  *extParam;
 	Bitmapset  *allParam;
+
+	/* info about applied extended statistics */
+	struct Applied_ExtStats *app_extstats;
 } Plan;
 
 /* ----------------
@@ -1617,4 +1620,16 @@ typedef enum MonotonicFunction
 	MONOTONICFUNC_BOTH = MONOTONICFUNC_INCREASING | MONOTONICFUNC_DECREASING,
 } MonotonicFunction;
 
+/*
+ * Applied_ExtStats - Information to show applied Extend Statistics
+ *
+ */
+typedef struct Applied_ExtStats
+{
+	NodeTag	type;
+	List    *applied_stats;
+	List    *applied_clauses;
+	List    *applied_clauses_or;
+} Applied_ExtStats;
+
 #endif							/* PLANNODES_H */
diff --git a/src/include/optimizer/restrictinfo.h b/src/include/optimizer/restrictinfo.h
index ec91fc9c583..0c34af43138 100644
--- a/src/include/optimizer/restrictinfo.h
+++ b/src/include/optimizer/restrictinfo.h
@@ -50,6 +50,8 @@ extern bool restriction_is_securely_promotable(RestrictInfo *restrictinfo,
 extern List *get_actual_clauses(List *restrictinfo_list);
 extern List *extract_actual_clauses(List *restrictinfo_list,
 									bool pseudoconstant);
+extern List *maybe_extract_actual_clauses(List *restrictinfo_list,
+										  bool pseudoconstant);
 extern void extract_actual_join_clauses(List *restrictinfo_list,
 										Relids joinrelids,
 										List **joinquals,
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 6fab7aa6009..f1e73e389c8 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -207,6 +207,9 @@ extern char *get_publication_name(Oid pubid, bool missing_ok);
 extern Oid	get_subscription_oid(const char *subname, bool missing_ok);
 extern char *get_subscription_name(Oid subid, bool missing_ok);
 
+extern char *get_statistics_name(Oid stxid);
+extern Oid	get_statistics_namespace(Oid stxid);
+
 #define type_is_array(typid)  (get_element_type(typid) != InvalidOid)
 /* type_is_array_domain accepts both plain arrays and domains over arrays */
 #define type_is_array_domain(typid)  (get_base_element_type(typid) != InvalidOid)
-- 
2.43.5