RFC: extensible planner state

From ee075b61cc988b165d8b697d4df287b462b9bf38 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 20 Aug 2025 15:10:52 -0400
Subject: [PATCH v2 2/2] Remove PlannerInfo's join_search_private method.

Instead, use the new mechanism that allows planner extensions to store
private state inside a PlannerInfo, treating GEQO as an in-core planner
extension.  This is a useful test of the new facility, and also buys
back a few bytes of storage.

To make this work, we must remove innerrel_is_unique_ext's hack of
testing whether join_search_private is set as a proxy for whether
the join search might be retried. Add a flag that extensions can
use to explicitly signal their intentions instead.
---
 src/backend/optimizer/geqo/geqo_eval.c    |  2 +-
 src/backend/optimizer/geqo/geqo_main.c    | 12 ++++++++++--
 src/backend/optimizer/geqo/geqo_random.c  |  7 +++----
 src/backend/optimizer/plan/analyzejoins.c |  9 +++------
 src/backend/optimizer/plan/planner.c      |  1 +
 src/backend/optimizer/prep/prepjointree.c |  1 +
 src/include/nodes/pathnodes.h             |  5 ++---
 src/include/optimizer/geqo.h              | 10 +++++++++-
 8 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/src/backend/optimizer/geqo/geqo_eval.c b/src/backend/optimizer/geqo/geqo_eval.c
index f07d1dc8ac6..7fcb1aa70d1 100644
--- a/src/backend/optimizer/geqo/geqo_eval.c
+++ b/src/backend/optimizer/geqo/geqo_eval.c
@@ -162,7 +162,7 @@ geqo_eval(PlannerInfo *root, Gene *tour, int num_gene)
 RelOptInfo *
 gimme_tree(PlannerInfo *root, Gene *tour, int num_gene)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 	List	   *clumps;
 	int			rel_count;
 
diff --git a/src/backend/optimizer/geqo/geqo_main.c b/src/backend/optimizer/geqo/geqo_main.c
index 38402ce58db..0064556087a 100644
--- a/src/backend/optimizer/geqo/geqo_main.c
+++ b/src/backend/optimizer/geqo/geqo_main.c
@@ -47,6 +47,8 @@ int			Geqo_generations;
 double		Geqo_selection_bias;
 double		Geqo_seed;
 
+/* GEQO is treated as an in-core planner extension */
+int			Geqo_planner_extension_id = -1;
 
 static int	gimme_pool_size(int nr_rel);
 static int	gimme_number_generations(int pool_size);
@@ -98,10 +100,16 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	int			mutations = 0;
 #endif
 
+	if (Geqo_planner_extension_id < 0)
+		Geqo_planner_extension_id = GetPlannerExtensionId("geqo");
+
 /* set up private information */
-	root->join_search_private = &private;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, &private);
 	private.initial_rels = initial_rels;
 
+/* inform core planner that we may replan */
+	root->assumeReplanning = true;
+
 /* initialize private number generator */
 	geqo_set_seed(root, Geqo_seed);
 
@@ -304,7 +312,7 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	free_pool(root, pool);
 
 	/* ... clear root pointer to our private storage */
-	root->join_search_private = NULL;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, NULL);
 
 	return best_rel;
 }
diff --git a/src/backend/optimizer/geqo/geqo_random.c b/src/backend/optimizer/geqo/geqo_random.c
index 6c7a411f69f..46d28baa2e6 100644
--- a/src/backend/optimizer/geqo/geqo_random.c
+++ b/src/backend/optimizer/geqo/geqo_random.c
@@ -15,11 +15,10 @@
 
 #include "optimizer/geqo_random.h"
 
-
 void
 geqo_set_seed(PlannerInfo *root, double seed)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	pg_prng_fseed(&private->random_state, seed);
 }
@@ -27,7 +26,7 @@ geqo_set_seed(PlannerInfo *root, double seed)
 double
 geqo_rand(PlannerInfo *root)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	return pg_prng_double(&private->random_state);
 }
@@ -35,7 +34,7 @@ geqo_rand(PlannerInfo *root)
 int
 geqo_randint(PlannerInfo *root, int upper, int lower)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	/*
 	 * In current usage, "lower" is never negative so we can just use
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 4d55c2ea591..82b3ab2e9f4 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -1425,17 +1425,14 @@ innerrel_is_unique_ext(PlannerInfo *root,
 		 *
 		 * However, in normal planning mode, caching this knowledge is totally
 		 * pointless; it won't be queried again, because we build up joinrels
-		 * from smaller to larger.  It is useful in GEQO mode, where the
-		 * knowledge can be carried across successive planning attempts; and
-		 * it's likely to be useful when using join-search plugins, too. Hence
-		 * cache when join_search_private is non-NULL.  (Yeah, that's a hack,
-		 * but it seems reasonable.)
+		 * from smaller to larger.  It's only useful when using GEQO or
+		 * another planner extension that attempts planning multiple times.
 		 *
 		 * Also, allow callers to override that heuristic and force caching;
 		 * that's useful for reduce_unique_semijoins, which calls here before
 		 * the normal join search starts.
 		 */
-		if (force_cache || root->join_search_private)
+		if (force_cache || root->assumeReplanning)
 		{
 			old_context = MemoryContextSwitchTo(root->planner_cxt);
 			innerrel->non_unique_for_rels =
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 0d5a692e5fd..926256da5f4 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -697,6 +697,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse, PlannerInfo *parent_root,
 	root->hasAlternativeSubPlans = false;
 	root->placeholdersFrozen = false;
 	root->hasRecursion = hasRecursion;
+	root->assumeReplanning = false;
 	if (hasRecursion)
 		root->wt_param_id = assign_special_exec_param(root);
 	else
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 35e8d3c183b..4075f7519ca 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -1383,6 +1383,7 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 	subroot->qual_security_level = 0;
 	subroot->placeholdersFrozen = false;
 	subroot->hasRecursion = false;
+	subroot->assumeReplanning = false;
 	subroot->wt_param_id = -1;
 	subroot->non_recursive_path = NULL;
 	/* We don't currently need a top JoinDomain for the subroot */
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index a32546c8848..8c1f0183413 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -536,6 +536,8 @@ struct PlannerInfo
 	bool		placeholdersFrozen;
 	/* true if planning a recursive WITH item */
 	bool		hasRecursion;
+	/* true if a planner extension may replan this subquery */
+	bool		assumeReplanning;
 
 	/*
 	 * The rangetable index for the RTE_GROUP RTE, or 0 if there is no
@@ -582,9 +584,6 @@ struct PlannerInfo
 	bool	   *isAltSubplan pg_node_attr(read_write_ignore);
 	bool	   *isUsedSubplan pg_node_attr(read_write_ignore);
 
-	/* optional private data for join_search_hook, e.g., GEQO */
-	void	   *join_search_private pg_node_attr(read_write_ignore);
-
 	/* Does this query modify any partition key columns? */
 	bool		partColsUpdated;
 
diff --git a/src/include/optimizer/geqo.h b/src/include/optimizer/geqo.h
index 9f8e0f337aa..3f4872e25e3 100644
--- a/src/include/optimizer/geqo.h
+++ b/src/include/optimizer/geqo.h
@@ -24,6 +24,7 @@
 
 #include "common/pg_prng.h"
 #include "nodes/pathnodes.h"
+#include "optimizer/extendplan.h"
 #include "optimizer/geqo_gene.h"
 
 
@@ -62,6 +63,8 @@ extern PGDLLIMPORT int Geqo_generations;	/* 1 .. inf, or 0 to use default */
 
 extern PGDLLIMPORT double Geqo_selection_bias;
 
+extern PGDLLIMPORT int Geqo_planner_extension_id;
+
 #define DEFAULT_GEQO_SELECTION_BIAS 2.0
 #define MIN_GEQO_SELECTION_BIAS 1.5
 #define MAX_GEQO_SELECTION_BIAS 2.0
@@ -70,7 +73,7 @@ extern PGDLLIMPORT double Geqo_seed;	/* 0 .. 1 */
 
 
 /*
- * Private state for a GEQO run --- accessible via root->join_search_private
+ * Private state for a GEQO run --- accessible via GetGeqoPrivateData
  */
 typedef struct
 {
@@ -78,6 +81,11 @@ typedef struct
 	pg_prng_state random_state; /* PRNG state */
 } GeqoPrivateData;
 
+static inline GeqoPrivateData *
+GetGeqoPrivateData(PlannerInfo *root)
+{
+	return GetPlannerInfoExtensionState(root, Geqo_planner_extension_id);
+}
 
 /* routines in geqo_main.c */
 extern RelOptInfo *geqo(PlannerInfo *root,
-- 
2.39.5 (Apple Git-154)

From d9bedbfb654d632c5c1b7c85c8bdca08f347f90b Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 18 Aug 2025 16:11:10 -0400
Subject: [PATCH v2 1/2] Allow private state in certain planner data
 structures.

Extension that make extensive use of planner hooks may want to
coordinate their efforts, for example to avoid duplicate computation,
but that's currently difficult because there's no really good way to
pass data between different hooks.

To make that easier, allow for storage of extension-managed private
state in PlannerGlobal, PlannerInfo, and RelOptInfo, along very
similar lines to what we have permitted for ExplainState since commit
c65bc2e1d14a2d4daed7c1921ac518f2c5ac3d17.
---
 src/backend/optimizer/util/Makefile     |   1 +
 src/backend/optimizer/util/extendplan.c | 181 ++++++++++++++++++++++++
 src/backend/optimizer/util/meson.build  |   1 +
 src/include/nodes/pathnodes.h           |  12 ++
 src/include/optimizer/extendplan.h      |  72 ++++++++++
 5 files changed, 267 insertions(+)
 create mode 100644 src/backend/optimizer/util/extendplan.c
 create mode 100644 src/include/optimizer/extendplan.h

diff --git a/src/backend/optimizer/util/Makefile b/src/backend/optimizer/util/Makefile
index 4fb115cb118..308730f392e 100644
--- a/src/backend/optimizer/util/Makefile
+++ b/src/backend/optimizer/util/Makefile
@@ -14,6 +14,7 @@ include $(top_builddir)/src/Makefile.global
 
 OBJS = \
 	appendinfo.o \
+	extendplan.o \
 	clauses.o \
 	inherit.o \
 	joininfo.o \
diff --git a/src/backend/optimizer/util/extendplan.c b/src/backend/optimizer/util/extendplan.c
new file mode 100644
index 00000000000..26b324d2ee6
--- /dev/null
+++ b/src/backend/optimizer/util/extendplan.c
@@ -0,0 +1,181 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.c
+ *	  Extend core planner objects with additional private state
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994-5, Regents of the University of California
+ *
+ * The interfaces defined in this file make it possible for loadable
+ * modules to their own private state inside of key planner data
+ * structures -- specifically, the PlannerGlobal, PlannerInfo, and
+ * RelOptInfo structures. This can make it much easier to write
+ * reasonably efficient planner extensions; for instance, code that
+ * uses set_join_pathlist_hook can arrange to compute a key intermediate
+ * result once per joinrel rather than on every call.
+ *
+ * IDENTIFICATION
+ *	  src/backend/commands/extendplan.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "optimizer/extendplan.h"
+#include "port/pg_bitutils.h"
+#include "utils/memutils.h"
+#include "utils/palloc.h"
+
+static const char **PlannerExtensionNameArray = NULL;
+static int	PlannerExtensionNamesAssigned = 0;
+static int	PlannerExtensionNamesAllocated = 0;
+
+/*
+ * Map the name of a planner extension to an integer ID.
+ *
+ * Within the lifetime of a particular backend, the same name will be mapped
+ * to the same ID every time. IDs are not stable across backends. Use the ID
+ * that you get from this function to call the remaining functions in this
+ * file.
+ */
+int
+GetPlannerExtensionId(const char *extension_name)
+{
+	/* Search for an existing extension by this name; if found, return ID. */
+	for (int i = 0; i < PlannerExtensionNamesAssigned; ++i)
+		if (strcmp(PlannerExtensionNameArray[i], extension_name) == 0)
+			return i;
+
+	/* If there is no array yet, create one. */
+	if (PlannerExtensionNameArray == NULL)
+	{
+		PlannerExtensionNamesAllocated = 16;
+		PlannerExtensionNameArray = (const char **)
+			MemoryContextAlloc(TopMemoryContext,
+							   PlannerExtensionNamesAllocated
+							   * sizeof(char *));
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (PlannerExtensionNamesAssigned >= PlannerExtensionNamesAllocated)
+	{
+		int			i = pg_nextpower2_32(PlannerExtensionNamesAssigned + 1);
+
+		PlannerExtensionNameArray = (const char **)
+			repalloc(PlannerExtensionNameArray, i * sizeof(char *));
+		PlannerExtensionNamesAllocated = i;
+	}
+
+	/* Assign and return new ID. */
+	PlannerExtensionNameArray[PlannerExtensionNamesAssigned] = extension_name;
+	return PlannerExtensionNamesAssigned++;
+}
+
+/*
+ * Store extension-specific state into a PlannerGlobal.
+ */
+void
+SetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id,
+							   void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (glob->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(glob);
+		glob->extension_state_allocated = 4;
+		sz = glob->extension_state_allocated * sizeof(void *);
+		glob->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= glob->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(glob->extension_state_allocated + 1);
+		glob->extension_state = (void **)
+			repalloc0(glob->extension_state,
+					  glob->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		glob->extension_state_allocated = i;
+	}
+
+	glob->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a PlannerInfo.
+ */
+void
+SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+							 void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (root->extension_state == NULL)
+	{
+		Size		sz;
+
+		root->extension_state_allocated = 4;
+		sz = root->extension_state_allocated * sizeof(void *);
+		root->extension_state = MemoryContextAllocZero(root->planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= root->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(root->extension_state_allocated + 1);
+		root->extension_state = (void **)
+			repalloc0(root->extension_state,
+					  root->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		root->extension_state_allocated = i;
+	}
+
+	root->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a RelOptInfo.
+ */
+void
+SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+							void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (rel->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(rel);
+		rel->extension_state_allocated = 4;
+		sz = rel->extension_state_allocated * sizeof(void *);
+		rel->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= rel->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(rel->extension_state_allocated + 1);
+		rel->extension_state = (void **)
+			repalloc0(rel->extension_state,
+					  rel->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		rel->extension_state_allocated = i;
+	}
+
+	rel->extension_state[extension_id] = opaque;
+}
diff --git a/src/backend/optimizer/util/meson.build b/src/backend/optimizer/util/meson.build
index b3bf913d096..f71f56e37a1 100644
--- a/src/backend/optimizer/util/meson.build
+++ b/src/backend/optimizer/util/meson.build
@@ -3,6 +3,7 @@
 backend_sources += files(
   'appendinfo.c',
   'clauses.c',
+  'extendplan.c',
   'inherit.c',
   'joininfo.c',
   'orclauses.c',
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index ad2726f026f..a32546c8848 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -182,6 +182,10 @@ typedef struct PlannerGlobal
 
 	/* hash table for NOT NULL attnums of relations */
 	struct HTAB *rel_notnullatts_hash pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } PlannerGlobal;
 
 /* macro for fetching the Plan associated with a SubPlan node */
@@ -586,6 +590,10 @@ struct PlannerInfo
 
 	/* PartitionPruneInfos added in this query's plan. */
 	List	   *partPruneInfos;
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 };
 
 
@@ -1075,6 +1083,10 @@ typedef struct RelOptInfo
 	List	  **partexprs pg_node_attr(read_write_ignore);
 	/* Nullable partition key expressions */
 	List	  **nullable_partexprs pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } RelOptInfo;
 
 /*
diff --git a/src/include/optimizer/extendplan.h b/src/include/optimizer/extendplan.h
new file mode 100644
index 00000000000..a6c89af31ef
--- /dev/null
+++ b/src/include/optimizer/extendplan.h
@@ -0,0 +1,72 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.h
+ *	  Extend core planner objects with additional private state
+ *
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/optimizer/extendplan.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef EXTENDPLAN_H
+#define EXTENDPLAN_H
+
+#include "nodes/pathnodes.h"
+
+extern int	GetPlannerExtensionId(const char *extension_name);
+
+/*
+ * Get extension-specific state from a PlannerGlobal.
+ */
+static inline void *
+GetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= glob->extension_state_allocated)
+		return NULL;
+
+	return glob->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetPlannerInfoExtensionState(PlannerInfo *root, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= root->extension_state_allocated)
+		return NULL;
+
+	return root->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= rel->extension_state_allocated)
+		return NULL;
+
+	return rel->extension_state[extension_id];
+}
+
+/* Functions to store private state into various planner objects */
+extern void SetPlannerGlobalExtensionState(PlannerGlobal *glob,
+										   int extension_id,
+										   void *opaque);
+extern void SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+										 void *opaque);
+extern void SetRelOptInfoExtensionState(RelOptInfo *root, int extension_id,
+										void *opaque);
+
+#endif
-- 
2.39.5 (Apple Git-154)

From 1aa43c063edb325548fa3db30b9991bf0831f6f5 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 18 Aug 2025 16:11:10 -0400
Subject: [PATCH v3 1/5] Allow private state in certain planner data
 structures.

Extension that make extensive use of planner hooks may want to
coordinate their efforts, for example to avoid duplicate computation,
but that's currently difficult because there's no really good way to
pass data between different hooks.

To make that easier, allow for storage of extension-managed private
state in PlannerGlobal, PlannerInfo, and RelOptInfo, along very
similar lines to what we have permitted for ExplainState since commit
c65bc2e1d14a2d4daed7c1921ac518f2c5ac3d17.
---
 src/backend/optimizer/util/Makefile     |   1 +
 src/backend/optimizer/util/extendplan.c | 181 ++++++++++++++++++++++++
 src/backend/optimizer/util/meson.build  |   1 +
 src/include/nodes/pathnodes.h           |  12 ++
 src/include/optimizer/extendplan.h      |  72 ++++++++++
 5 files changed, 267 insertions(+)
 create mode 100644 src/backend/optimizer/util/extendplan.c
 create mode 100644 src/include/optimizer/extendplan.h

diff --git a/src/backend/optimizer/util/Makefile b/src/backend/optimizer/util/Makefile
index 4fb115cb118..308730f392e 100644
--- a/src/backend/optimizer/util/Makefile
+++ b/src/backend/optimizer/util/Makefile
@@ -14,6 +14,7 @@ include $(top_builddir)/src/Makefile.global
 
 OBJS = \
 	appendinfo.o \
+	extendplan.o \
 	clauses.o \
 	inherit.o \
 	joininfo.o \
diff --git a/src/backend/optimizer/util/extendplan.c b/src/backend/optimizer/util/extendplan.c
new file mode 100644
index 00000000000..26b324d2ee6
--- /dev/null
+++ b/src/backend/optimizer/util/extendplan.c
@@ -0,0 +1,181 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.c
+ *	  Extend core planner objects with additional private state
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994-5, Regents of the University of California
+ *
+ * The interfaces defined in this file make it possible for loadable
+ * modules to their own private state inside of key planner data
+ * structures -- specifically, the PlannerGlobal, PlannerInfo, and
+ * RelOptInfo structures. This can make it much easier to write
+ * reasonably efficient planner extensions; for instance, code that
+ * uses set_join_pathlist_hook can arrange to compute a key intermediate
+ * result once per joinrel rather than on every call.
+ *
+ * IDENTIFICATION
+ *	  src/backend/commands/extendplan.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "optimizer/extendplan.h"
+#include "port/pg_bitutils.h"
+#include "utils/memutils.h"
+#include "utils/palloc.h"
+
+static const char **PlannerExtensionNameArray = NULL;
+static int	PlannerExtensionNamesAssigned = 0;
+static int	PlannerExtensionNamesAllocated = 0;
+
+/*
+ * Map the name of a planner extension to an integer ID.
+ *
+ * Within the lifetime of a particular backend, the same name will be mapped
+ * to the same ID every time. IDs are not stable across backends. Use the ID
+ * that you get from this function to call the remaining functions in this
+ * file.
+ */
+int
+GetPlannerExtensionId(const char *extension_name)
+{
+	/* Search for an existing extension by this name; if found, return ID. */
+	for (int i = 0; i < PlannerExtensionNamesAssigned; ++i)
+		if (strcmp(PlannerExtensionNameArray[i], extension_name) == 0)
+			return i;
+
+	/* If there is no array yet, create one. */
+	if (PlannerExtensionNameArray == NULL)
+	{
+		PlannerExtensionNamesAllocated = 16;
+		PlannerExtensionNameArray = (const char **)
+			MemoryContextAlloc(TopMemoryContext,
+							   PlannerExtensionNamesAllocated
+							   * sizeof(char *));
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (PlannerExtensionNamesAssigned >= PlannerExtensionNamesAllocated)
+	{
+		int			i = pg_nextpower2_32(PlannerExtensionNamesAssigned + 1);
+
+		PlannerExtensionNameArray = (const char **)
+			repalloc(PlannerExtensionNameArray, i * sizeof(char *));
+		PlannerExtensionNamesAllocated = i;
+	}
+
+	/* Assign and return new ID. */
+	PlannerExtensionNameArray[PlannerExtensionNamesAssigned] = extension_name;
+	return PlannerExtensionNamesAssigned++;
+}
+
+/*
+ * Store extension-specific state into a PlannerGlobal.
+ */
+void
+SetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id,
+							   void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (glob->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(glob);
+		glob->extension_state_allocated = 4;
+		sz = glob->extension_state_allocated * sizeof(void *);
+		glob->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= glob->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(glob->extension_state_allocated + 1);
+		glob->extension_state = (void **)
+			repalloc0(glob->extension_state,
+					  glob->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		glob->extension_state_allocated = i;
+	}
+
+	glob->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a PlannerInfo.
+ */
+void
+SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+							 void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (root->extension_state == NULL)
+	{
+		Size		sz;
+
+		root->extension_state_allocated = 4;
+		sz = root->extension_state_allocated * sizeof(void *);
+		root->extension_state = MemoryContextAllocZero(root->planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= root->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(root->extension_state_allocated + 1);
+		root->extension_state = (void **)
+			repalloc0(root->extension_state,
+					  root->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		root->extension_state_allocated = i;
+	}
+
+	root->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a RelOptInfo.
+ */
+void
+SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+							void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (rel->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(rel);
+		rel->extension_state_allocated = 4;
+		sz = rel->extension_state_allocated * sizeof(void *);
+		rel->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= rel->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(rel->extension_state_allocated + 1);
+		rel->extension_state = (void **)
+			repalloc0(rel->extension_state,
+					  rel->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		rel->extension_state_allocated = i;
+	}
+
+	rel->extension_state[extension_id] = opaque;
+}
diff --git a/src/backend/optimizer/util/meson.build b/src/backend/optimizer/util/meson.build
index b3bf913d096..f71f56e37a1 100644
--- a/src/backend/optimizer/util/meson.build
+++ b/src/backend/optimizer/util/meson.build
@@ -3,6 +3,7 @@
 backend_sources += files(
   'appendinfo.c',
   'clauses.c',
+  'extendplan.c',
   'inherit.c',
   'joininfo.c',
   'orclauses.c',
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 4a903d1ec18..21df16f5b04 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -182,6 +182,10 @@ typedef struct PlannerGlobal
 
 	/* hash table for NOT NULL attnums of relations */
 	struct HTAB *rel_notnullatts_hash pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } PlannerGlobal;
 
 /* macro for fetching the Plan associated with a SubPlan node */
@@ -586,6 +590,10 @@ struct PlannerInfo
 
 	/* PartitionPruneInfos added in this query's plan. */
 	List	   *partPruneInfos;
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 };
 
 
@@ -1097,6 +1105,10 @@ typedef struct RelOptInfo
 	List	  **partexprs pg_node_attr(read_write_ignore);
 	/* Nullable partition key expressions */
 	List	  **nullable_partexprs pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } RelOptInfo;
 
 /*
diff --git a/src/include/optimizer/extendplan.h b/src/include/optimizer/extendplan.h
new file mode 100644
index 00000000000..a6c89af31ef
--- /dev/null
+++ b/src/include/optimizer/extendplan.h
@@ -0,0 +1,72 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.h
+ *	  Extend core planner objects with additional private state
+ *
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/optimizer/extendplan.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef EXTENDPLAN_H
+#define EXTENDPLAN_H
+
+#include "nodes/pathnodes.h"
+
+extern int	GetPlannerExtensionId(const char *extension_name);
+
+/*
+ * Get extension-specific state from a PlannerGlobal.
+ */
+static inline void *
+GetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= glob->extension_state_allocated)
+		return NULL;
+
+	return glob->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetPlannerInfoExtensionState(PlannerInfo *root, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= root->extension_state_allocated)
+		return NULL;
+
+	return root->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= rel->extension_state_allocated)
+		return NULL;
+
+	return rel->extension_state[extension_id];
+}
+
+/* Functions to store private state into various planner objects */
+extern void SetPlannerGlobalExtensionState(PlannerGlobal *glob,
+										   int extension_id,
+										   void *opaque);
+extern void SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+										 void *opaque);
+extern void SetRelOptInfoExtensionState(RelOptInfo *root, int extension_id,
+										void *opaque);
+
+#endif
-- 
2.39.5 (Apple Git-154)

From 6e17282a078941a669d4e0da720d9642daeee4b1 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 20 Aug 2025 15:10:52 -0400
Subject: [PATCH v3 2/5] Remove PlannerInfo's join_search_private method.

Instead, use the new mechanism that allows planner extensions to store
private state inside a PlannerInfo, treating GEQO as an in-core planner
extension.  This is a useful test of the new facility, and also buys
back a few bytes of storage.

To make this work, we must remove innerrel_is_unique_ext's hack of
testing whether join_search_private is set as a proxy for whether
the join search might be retried. Add a flag that extensions can
use to explicitly signal their intentions instead.
---
 src/backend/optimizer/geqo/geqo_eval.c    |  2 +-
 src/backend/optimizer/geqo/geqo_main.c    | 12 ++++++++++--
 src/backend/optimizer/geqo/geqo_random.c  |  7 +++----
 src/backend/optimizer/plan/analyzejoins.c |  9 +++------
 src/backend/optimizer/plan/planner.c      |  1 +
 src/backend/optimizer/prep/prepjointree.c |  1 +
 src/include/nodes/pathnodes.h             |  5 ++---
 src/include/optimizer/geqo.h              | 10 +++++++++-
 8 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/src/backend/optimizer/geqo/geqo_eval.c b/src/backend/optimizer/geqo/geqo_eval.c
index f07d1dc8ac6..7fcb1aa70d1 100644
--- a/src/backend/optimizer/geqo/geqo_eval.c
+++ b/src/backend/optimizer/geqo/geqo_eval.c
@@ -162,7 +162,7 @@ geqo_eval(PlannerInfo *root, Gene *tour, int num_gene)
 RelOptInfo *
 gimme_tree(PlannerInfo *root, Gene *tour, int num_gene)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 	List	   *clumps;
 	int			rel_count;
 
diff --git a/src/backend/optimizer/geqo/geqo_main.c b/src/backend/optimizer/geqo/geqo_main.c
index 38402ce58db..0064556087a 100644
--- a/src/backend/optimizer/geqo/geqo_main.c
+++ b/src/backend/optimizer/geqo/geqo_main.c
@@ -47,6 +47,8 @@ int			Geqo_generations;
 double		Geqo_selection_bias;
 double		Geqo_seed;
 
+/* GEQO is treated as an in-core planner extension */
+int			Geqo_planner_extension_id = -1;
 
 static int	gimme_pool_size(int nr_rel);
 static int	gimme_number_generations(int pool_size);
@@ -98,10 +100,16 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	int			mutations = 0;
 #endif
 
+	if (Geqo_planner_extension_id < 0)
+		Geqo_planner_extension_id = GetPlannerExtensionId("geqo");
+
 /* set up private information */
-	root->join_search_private = &private;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, &private);
 	private.initial_rels = initial_rels;
 
+/* inform core planner that we may replan */
+	root->assumeReplanning = true;
+
 /* initialize private number generator */
 	geqo_set_seed(root, Geqo_seed);
 
@@ -304,7 +312,7 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	free_pool(root, pool);
 
 	/* ... clear root pointer to our private storage */
-	root->join_search_private = NULL;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, NULL);
 
 	return best_rel;
 }
diff --git a/src/backend/optimizer/geqo/geqo_random.c b/src/backend/optimizer/geqo/geqo_random.c
index 6c7a411f69f..46d28baa2e6 100644
--- a/src/backend/optimizer/geqo/geqo_random.c
+++ b/src/backend/optimizer/geqo/geqo_random.c
@@ -15,11 +15,10 @@
 
 #include "optimizer/geqo_random.h"
 
-
 void
 geqo_set_seed(PlannerInfo *root, double seed)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	pg_prng_fseed(&private->random_state, seed);
 }
@@ -27,7 +26,7 @@ geqo_set_seed(PlannerInfo *root, double seed)
 double
 geqo_rand(PlannerInfo *root)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	return pg_prng_double(&private->random_state);
 }
@@ -35,7 +34,7 @@ geqo_rand(PlannerInfo *root)
 int
 geqo_randint(PlannerInfo *root, int upper, int lower)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	/*
 	 * In current usage, "lower" is never negative so we can just use
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index da92d8ee414..60b37ac6cd0 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -1424,17 +1424,14 @@ innerrel_is_unique_ext(PlannerInfo *root,
 		 *
 		 * However, in normal planning mode, caching this knowledge is totally
 		 * pointless; it won't be queried again, because we build up joinrels
-		 * from smaller to larger.  It is useful in GEQO mode, where the
-		 * knowledge can be carried across successive planning attempts; and
-		 * it's likely to be useful when using join-search plugins, too. Hence
-		 * cache when join_search_private is non-NULL.  (Yeah, that's a hack,
-		 * but it seems reasonable.)
+		 * from smaller to larger.  It's only useful when using GEQO or
+		 * another planner extension that attempts planning multiple times.
 		 *
 		 * Also, allow callers to override that heuristic and force caching;
 		 * that's useful for reduce_unique_semijoins, which calls here before
 		 * the normal join search starts.
 		 */
-		if (force_cache || root->join_search_private)
+		if (force_cache || root->assumeReplanning)
 		{
 			old_context = MemoryContextSwitchTo(root->planner_cxt);
 			innerrel->non_unique_for_rels =
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 65f17101591..0ffe8cf12c6 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -703,6 +703,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse, PlannerInfo *parent_root,
 	root->hasAlternativeSubPlans = false;
 	root->placeholdersFrozen = false;
 	root->hasRecursion = hasRecursion;
+	root->assumeReplanning = false;
 	if (hasRecursion)
 		root->wt_param_id = assign_special_exec_param(root);
 	else
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 35e8d3c183b..4075f7519ca 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -1383,6 +1383,7 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 	subroot->qual_security_level = 0;
 	subroot->placeholdersFrozen = false;
 	subroot->hasRecursion = false;
+	subroot->assumeReplanning = false;
 	subroot->wt_param_id = -1;
 	subroot->non_recursive_path = NULL;
 	/* We don't currently need a top JoinDomain for the subroot */
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 21df16f5b04..641e77a1326 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -536,6 +536,8 @@ struct PlannerInfo
 	bool		placeholdersFrozen;
 	/* true if planning a recursive WITH item */
 	bool		hasRecursion;
+	/* true if a planner extension may replan this subquery */
+	bool		assumeReplanning;
 
 	/*
 	 * The rangetable index for the RTE_GROUP RTE, or 0 if there is no
@@ -582,9 +584,6 @@ struct PlannerInfo
 	bool	   *isAltSubplan pg_node_attr(read_write_ignore);
 	bool	   *isUsedSubplan pg_node_attr(read_write_ignore);
 
-	/* optional private data for join_search_hook, e.g., GEQO */
-	void	   *join_search_private pg_node_attr(read_write_ignore);
-
 	/* Does this query modify any partition key columns? */
 	bool		partColsUpdated;
 
diff --git a/src/include/optimizer/geqo.h b/src/include/optimizer/geqo.h
index 9f8e0f337aa..3f4872e25e3 100644
--- a/src/include/optimizer/geqo.h
+++ b/src/include/optimizer/geqo.h
@@ -24,6 +24,7 @@
 
 #include "common/pg_prng.h"
 #include "nodes/pathnodes.h"
+#include "optimizer/extendplan.h"
 #include "optimizer/geqo_gene.h"
 
 
@@ -62,6 +63,8 @@ extern PGDLLIMPORT int Geqo_generations;	/* 1 .. inf, or 0 to use default */
 
 extern PGDLLIMPORT double Geqo_selection_bias;
 
+extern PGDLLIMPORT int Geqo_planner_extension_id;
+
 #define DEFAULT_GEQO_SELECTION_BIAS 2.0
 #define MIN_GEQO_SELECTION_BIAS 1.5
 #define MAX_GEQO_SELECTION_BIAS 2.0
@@ -70,7 +73,7 @@ extern PGDLLIMPORT double Geqo_seed;	/* 0 .. 1 */
 
 
 /*
- * Private state for a GEQO run --- accessible via root->join_search_private
+ * Private state for a GEQO run --- accessible via GetGeqoPrivateData
  */
 typedef struct
 {
@@ -78,6 +81,11 @@ typedef struct
 	pg_prng_state random_state; /* PRNG state */
 } GeqoPrivateData;
 
+static inline GeqoPrivateData *
+GetGeqoPrivateData(PlannerInfo *root)
+{
+	return GetPlannerInfoExtensionState(root, Geqo_planner_extension_id);
+}
 
 /* routines in geqo_main.c */
 extern RelOptInfo *geqo(PlannerInfo *root,
-- 
2.39.5 (Apple Git-154)

From 641cf91bf28d2f449f2b6b87d75bfe5cd27298f3 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 15:22:57 -0400
Subject: [PATCH v3 5/5] not for commit: count distinct joinrels and joinrel
 planning attempts

---
 .../expected/pg_overexplain.out               |  22 +++-
 contrib/pg_overexplain/pg_overexplain.c       | 107 ++++++++++++++++++
 2 files changed, 124 insertions(+), 5 deletions(-)

diff --git a/contrib/pg_overexplain/expected/pg_overexplain.out b/contrib/pg_overexplain/expected/pg_overexplain.out
index 6de02323d7c..d8d3e36d7f1 100644
--- a/contrib/pg_overexplain/expected/pg_overexplain.out
+++ b/contrib/pg_overexplain/expected/pg_overexplain.out
@@ -38,7 +38,9 @@ EXPLAIN (DEBUG) SELECT 1;
    Relation OIDs: none
    Executor Parameter Types: none
    Parse Location: 0 to end
-(11 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(13 rows)
 
 EXPLAIN (RANGE_TABLE) SELECT 1;
                 QUERY PLAN                
@@ -120,6 +122,8 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
  RTI 1 (relation, inherited, in-from-clause):
    Eref: vegetables (id, name, genus)
    Relation: vegetables
@@ -141,7 +145,7 @@ $$);
    Relation Kind: relation
    Relation Lock Mode: AccessShareLock
  Unprunable RTIs: 1 3 4
-(53 rows)
+(55 rows)
 
 -- Test a different output format.
 SELECT explain_filter($$
@@ -241,6 +245,8 @@ $$);
        <Relation-OIDs>NNN...</Relation-OIDs>                        +
        <Executor-Parameter-Types>none</Executor-Parameter-Types>    +
        <Parse-Location>0 to end</Parse-Location>                    +
+       <Total-Joinrel-Attempts>0</Total-Joinrel-Attempts>           +
+       <Distinct-Joinrels>0</Distinct-Joinrels>                     +
      </PlannedStmt>                                                 +
      <Range-Table>                                                  +
        <Range-Table-Entry>                                          +
@@ -345,7 +351,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
-(37 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(39 rows)
 
 SET debug_parallel_query = false;
 RESET enable_seqscan;
@@ -373,7 +381,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 0
    Parse Location: 0 to end
-(15 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(17 rows)
 
 -- Create an index, and then attempt to force a nested loop with inner index
 -- scan so that we can see parameter-related information. Also, let's try
@@ -437,7 +447,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 23
    Parse Location: 0 to end
-(47 rows)
+   Total Joinrel Attempts: 2
+   Distinct Joinrels: 1
+(49 rows)
 
 RESET enable_hashjoin;
 RESET enable_material;
diff --git a/contrib/pg_overexplain/pg_overexplain.c b/contrib/pg_overexplain/pg_overexplain.c
index de824566f8c..bf4852fcadc 100644
--- a/contrib/pg_overexplain/pg_overexplain.c
+++ b/contrib/pg_overexplain/pg_overexplain.c
@@ -16,6 +16,10 @@
 #include "commands/explain_format.h"
 #include "commands/explain_state.h"
 #include "fmgr.h"
+#include "nodes/makefuncs.h"
+#include "optimizer/extendplan.h"
+#include "optimizer/paths.h"
+#include "optimizer/planner.h"
 #include "parser/parsetree.h"
 #include "storage/lock.h"
 #include "utils/builtins.h"
@@ -32,6 +36,12 @@ typedef struct
 	bool		range_table;
 } overexplain_options;
 
+typedef struct
+{
+	int			total_joinrel_attempts;
+	int			distinct_joinrel_count;
+} overexplain_plannerglobal;
+
 static overexplain_options *overexplain_ensure_options(ExplainState *es);
 static void overexplain_debug_handler(ExplainState *es, DefElem *opt,
 									  ParseState *pstate);
@@ -57,9 +67,27 @@ static void overexplain_bitmapset(const char *qlabel, Bitmapset *bms,
 static void overexplain_intlist(const char *qlabel, List *list,
 								ExplainState *es);
 
+static void overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+										   const char *query_string,
+										   double *tuple_fraction);
+static void overexplain_planner_shutdown_hook(PlannerGlobal *glob,
+											  Query *parse,
+											  const char *query_string,
+											  PlannedStmt *pstmt);
+static void overexplain_set_join_pathlist_hook(PlannerInfo *root,
+											   RelOptInfo *joinrel,
+											   RelOptInfo *outerrel,
+											   RelOptInfo *innerrel,
+											   JoinType jointype,
+											   JoinPathExtraData *extra);
+
 static int	es_extension_id;
+static int	planner_extension_id = -1;
 static explain_per_node_hook_type prev_explain_per_node_hook;
 static explain_per_plan_hook_type prev_explain_per_plan_hook;
+static planner_setup_hook_type prev_planner_setup_hook;
+static planner_shutdown_hook_type prev_planner_shutdown_hook;
+static set_join_pathlist_hook_type prev_set_join_pathlist_hook;
 
 /*
  * Initialization we do when this module is loaded.
@@ -70,6 +98,9 @@ _PG_init(void)
 	/* Get an ID that we can use to cache data in an ExplainState. */
 	es_extension_id = GetExplainExtensionId("pg_overexplain");
 
+	/* Get an ID that we can use to cache data in the planner. */
+	planner_extension_id = GetPlannerExtensionId("pg_overexplain");
+
 	/* Register the new EXPLAIN options implemented by this module. */
 	RegisterExtensionExplainOption("debug", overexplain_debug_handler);
 	RegisterExtensionExplainOption("range_table",
@@ -80,6 +111,16 @@ _PG_init(void)
 	explain_per_node_hook = overexplain_per_node_hook;
 	prev_explain_per_plan_hook = explain_per_plan_hook;
 	explain_per_plan_hook = overexplain_per_plan_hook;
+
+	/* Example of planner_setup_hook/planner_shutdown_hook use */
+	prev_planner_setup_hook = planner_setup_hook;
+	planner_setup_hook = overexplain_planner_setup_hook;
+	prev_planner_shutdown_hook = planner_shutdown_hook;
+	planner_shutdown_hook = overexplain_planner_shutdown_hook;
+
+	/* Support for above example */
+	prev_set_join_pathlist_hook = set_join_pathlist_hook;
+	set_join_pathlist_hook = overexplain_set_join_pathlist_hook;
 }
 
 /*
@@ -369,6 +410,29 @@ overexplain_debug(PlannedStmt *plannedstmt, ExplainState *es)
 									 plannedstmt->stmt_len),
 							es);
 
+	{
+		DefElem    *elem = NULL;
+
+		foreach_node(DefElem, de, plannedstmt->extension_state)
+		{
+			if (strcmp(de->defname, "pg_overexplain") == 0)
+			{
+				elem = de;
+				break;
+			}
+		}
+
+		if (elem != NULL)
+		{
+			List	   *l = castNode(List, elem->arg);
+
+			ExplainPropertyInteger("Total Joinrel Attempts", NULL,
+								   intVal(linitial(l)), es);
+			ExplainPropertyInteger("Distinct Joinrels", NULL,
+								   intVal(lsecond(l)), es);
+		}
+	}
+
 	/* Done with this group. */
 	if (es->format == EXPLAIN_FORMAT_TEXT)
 		es->indent--;
@@ -772,3 +836,46 @@ overexplain_intlist(const char *qlabel, List *list, ExplainState *es)
 
 	pfree(buf.data);
 }
+
+static void
+overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+							   const char *query_string,
+							   double *tuple_fraction)
+{
+	overexplain_plannerglobal *g = palloc0_object(overexplain_plannerglobal);
+
+	SetPlannerGlobalExtensionState(glob, planner_extension_id, g);
+}
+
+static void
+overexplain_planner_shutdown_hook(PlannerGlobal *glob, Query *parse,
+								  const char *query_string, PlannedStmt *pstmt)
+{
+	overexplain_plannerglobal *g;
+	DefElem    *elem;
+	List	   *l;
+
+	g = GetPlannerGlobalExtensionState(glob, planner_extension_id);
+	l = list_make2(makeInteger(g->total_joinrel_attempts),
+				   makeInteger(g->distinct_joinrel_count));
+	elem = makeDefElem("pg_overexplain", (Node *) l, -1);
+	pstmt->extension_state = lappend(pstmt->extension_state, elem);
+}
+
+static void
+overexplain_set_join_pathlist_hook(PlannerInfo *root, RelOptInfo *joinrel,
+								   RelOptInfo *outerrel, RelOptInfo *innerrel,
+								   JoinType jointype, JoinPathExtraData *extra)
+{
+	overexplain_plannerglobal *g;
+
+	g = GetPlannerGlobalExtensionState(root->glob, planner_extension_id);
+	g->total_joinrel_attempts++;
+
+	if (GetRelOptInfoExtensionState(joinrel, planner_extension_id) == NULL)
+	{
+		g->distinct_joinrel_count++;
+		/* set any non-NULL value to avoid double-counting */
+		SetRelOptInfoExtensionState(joinrel, planner_extension_id, g);
+	}
+}
-- 
2.39.5 (Apple Git-154)

From 85dc4e21a7c660e4966bd461f64b5ba3d9a743b3 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 13:04:50 -0400
Subject: [PATCH v3 3/5] Add planner_setup_hook and planner_shutdown_hook.

These hooks allow plugins to get control at the earliest point at
which the PlannerGlobal object is fully initialized, and then just
before it gets destroyed. This is useful in combination with the
extendable plan state facilities (see extendplan.h) and perhaps for
other purposes as well.
---
 src/backend/optimizer/plan/planner.c | 14 ++++++++++++++
 src/include/optimizer/planner.h      | 12 ++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 0ffe8cf12c6..407ba34fc47 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -73,6 +73,12 @@ bool		enable_distinct_reordering = true;
 /* Hook for plugins to get control in planner() */
 planner_hook_type planner_hook = NULL;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+planner_setup_hook_type planner_setup_hook = NULL;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+planner_shutdown_hook_type planner_shutdown_hook = NULL;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 create_upper_paths_hook_type create_upper_paths_hook = NULL;
 
@@ -438,6 +444,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 		tuple_fraction = 0.0;
 	}
 
+	/* Allow plugins to take control after we've initialized "glob" */
+	if (planner_setup_hook)
+		(*planner_setup_hook) (glob, parse, query_string, &tuple_fraction);
+
 	/* primary planning entry point (may recurse for subqueries) */
 	root = subquery_planner(glob, parse, NULL, false, tuple_fraction, NULL);
 
@@ -619,6 +629,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 	if (glob->partition_directory != NULL)
 		DestroyPartitionDirectory(glob->partition_directory);
 
+	/* Allow plugins to take control before we discard "glob" */
+	if (planner_shutdown_hook)
+		(*planner_shutdown_hook) (glob, parse, query_string, result);
+
 	return result;
 }
 
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index f220e9a270d..732f8f81171 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -29,6 +29,18 @@ typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   ParamListInfo boundParams);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+typedef void (*planner_setup_hook_type) (PlannerGlobal *glob, Query *parse,
+										 const char *query_string,
+										 double *tuple_fraction);
+extern PGDLLIMPORT planner_setup_hook_type planner_setup_hook;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+typedef void (*planner_shutdown_hook_type) (PlannerGlobal *glob, Query *parse,
+											const char *query_string,
+											PlannedStmt *pstmt);
+extern PGDLLIMPORT planner_shutdown_hook_type planner_shutdown_hook;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 typedef void (*create_upper_paths_hook_type) (PlannerInfo *root,
 											  UpperRelationKind stage,
-- 
2.39.5 (Apple Git-154)

From b91c3d7792ba19fc57871f7fb62352f9cb2e0337 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 14:29:02 -0400
Subject: [PATCH v3 4/5] Add extension_state member to PlannedStmt.

Extensions can stash data computed at plan time into this list using
planner_shutdown_hook (or perhaps other mechanisms) and then access
it from any code that has access to the PlannedStmt (such as explain
hooks), allowing for extensible debugging and instrumentation of
plans.
---
 src/include/nodes/plannodes.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 29d7732d6a0..326c3f7fe6f 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -149,6 +149,15 @@ typedef struct PlannedStmt
 	/* non-null if this is utility stmt */
 	Node	   *utilityStmt;
 
+	/*
+	 * DefElem objects added by extensions, e.g. using planner_shutdown_hook
+	 *
+	 * Set each DefElem's defname to the name of the plugin or extension, and
+	 * the argument to a tree of nodes that all have copy and read/write
+	 * support.
+	 */
+	List	   *extension_state;
+
 	/* statement location in source string (copied from Query) */
 	/* start location, or -1 if unknown */
 	ParseLoc	stmt_location;
-- 
2.39.5 (Apple Git-154)

From 8c911c8ddc832e56a5711e5e34a58b254e5f68f9 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 16 Sep 2025 13:13:24 -0400
Subject: [PATCH v4 3/6] Add ExplainState argument to pg_plan_query() and
 planner().

This allows extensions to have access to any data they've stored
in the ExplainState during planning. Unfortunately, it won't help
with EXPLAIN EXECUTE is used, but since that case is less common,
this still seems like an improvement.
---
 contrib/pg_stat_statements/pg_stat_statements.c    | 14 ++++++++------
 src/backend/commands/copyto.c                      |  2 +-
 src/backend/commands/createas.c                    |  2 +-
 src/backend/commands/explain.c                     |  4 ++--
 src/backend/commands/matview.c                     |  2 +-
 src/backend/commands/portalcmds.c                  |  3 ++-
 src/backend/optimizer/plan/planner.c               | 10 ++++++----
 src/backend/tcop/postgres.c                        |  7 ++++---
 src/include/optimizer/optimizer.h                  |  6 +++++-
 src/include/optimizer/planner.h                    |  9 +++++++--
 src/include/tcop/tcopprot.h                        |  5 ++++-
 src/test/modules/delay_execution/delay_execution.c |  7 ++++---
 12 files changed, 45 insertions(+), 26 deletions(-)

diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 0bb0f933399..0eb208f58fc 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -337,7 +337,8 @@ static void pgss_post_parse_analyze(ParseState *pstate, Query *query,
 static PlannedStmt *pgss_planner(Query *parse,
 								 const char *query_string,
 								 int cursorOptions,
-								 ParamListInfo boundParams);
+								 ParamListInfo boundParams,
+								 struct ExplainState *es);
 static void pgss_ExecutorStart(QueryDesc *queryDesc, int eflags);
 static void pgss_ExecutorRun(QueryDesc *queryDesc,
 							 ScanDirection direction,
@@ -893,7 +894,8 @@ static PlannedStmt *
 pgss_planner(Query *parse,
 			 const char *query_string,
 			 int cursorOptions,
-			 ParamListInfo boundParams)
+			 ParamListInfo boundParams,
+			 struct ExplainState *es)
 {
 	PlannedStmt *result;
 
@@ -928,10 +930,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
@@ -977,10 +979,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
diff --git a/src/backend/commands/copyto.c b/src/backend/commands/copyto.c
index 67b94b91cae..e5781155cdf 100644
--- a/src/backend/commands/copyto.c
+++ b/src/backend/commands/copyto.c
@@ -796,7 +796,7 @@ BeginCopyTo(ParseState *pstate,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, NULL);
+							 CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 		/*
 		 * With row-level security and a user using "COPY relation TO", we
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1ccc2e55c64 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -321,7 +321,7 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, params);
+							 CURSOR_OPT_PARALLEL_OK, params, NULL);
 
 		/*
 		 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index c3d449fdec1..9f0fc3206e3 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -351,7 +351,7 @@ standard_ExplainOneQuery(Query *query, int cursorOptions,
 	INSTR_TIME_SET_CURRENT(planstart);
 
 	/* plan the query */
-	plan = pg_plan_query(query, queryString, cursorOptions, params);
+	plan = pg_plan_query(query, queryString, cursorOptions, params, es);
 
 	INSTR_TIME_SET_CURRENT(planduration);
 	INSTR_TIME_SUBTRACT(planduration, planstart);
@@ -4853,7 +4853,7 @@ show_result_replacement_info(Result *result, ExplainState *es)
 		ExplainPropertyText("Replaces", replacement_type, es);
 	else
 	{
-		char *s = psprintf("%s on %s", replacement_type, buf.data);
+		char	   *s = psprintf("%s on %s", replacement_type, buf.data);
 
 		ExplainPropertyText("Replaces", s, es);
 	}
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 188e26f0e6e..441de55ac24 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -426,7 +426,7 @@ refresh_matview_datafill(DestReceiver *dest, Query *query,
 	CHECK_FOR_INTERRUPTS();
 
 	/* Plan the query which will generate data for the refresh. */
-	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL);
+	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 	/*
 	 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c
index e7c8171c102..ec96c2efcd3 100644
--- a/src/backend/commands/portalcmds.c
+++ b/src/backend/commands/portalcmds.c
@@ -99,7 +99,8 @@ PerformCursorOpen(ParseState *pstate, DeclareCursorStmt *cstmt, ParamListInfo pa
 		elog(ERROR, "non-SELECT statement in DECLARE CURSOR");
 
 	/* Plan the query, applying the specified options */
-	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params);
+	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params,
+						 NULL);
 
 	/*
 	 * Create a portal and copy the plan and query string into its memory.
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 9de39da1757..205d8886a2a 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -291,14 +291,16 @@ static void create_partial_unique_paths(PlannerInfo *root, RelOptInfo *input_rel
  *****************************************************************************/
 PlannedStmt *
 planner(Query *parse, const char *query_string, int cursorOptions,
-		ParamListInfo boundParams)
+		ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 
 	if (planner_hook)
-		result = (*planner_hook) (parse, query_string, cursorOptions, boundParams);
+		result = (*planner_hook) (parse, query_string, cursorOptions,
+								  boundParams, es);
 	else
-		result = standard_planner(parse, query_string, cursorOptions, boundParams);
+		result = standard_planner(parse, query_string, cursorOptions,
+								  boundParams, es);
 
 	pgstat_report_plan_id(result->planId, false);
 
@@ -307,7 +309,7 @@ planner(Query *parse, const char *query_string, int cursorOptions,
 
 PlannedStmt *
 standard_planner(Query *parse, const char *query_string, int cursorOptions,
-				 ParamListInfo boundParams)
+				 ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 	PlannerGlobal *glob;
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index d356830f756..7dd75a490aa 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -37,6 +37,7 @@
 #include "catalog/pg_type.h"
 #include "commands/async.h"
 #include "commands/event_trigger.h"
+#include "commands/explain_state.h"
 #include "commands/prepare.h"
 #include "common/pg_prng.h"
 #include "jit/jit.h"
@@ -884,7 +885,7 @@ pg_rewrite_query(Query *query)
  */
 PlannedStmt *
 pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
-			  ParamListInfo boundParams)
+			  ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *plan;
 
@@ -901,7 +902,7 @@ pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
 		ResetUsage();
 
 	/* call the optimizer */
-	plan = planner(querytree, query_string, cursorOptions, boundParams);
+	plan = planner(querytree, query_string, cursorOptions, boundParams, es);
 
 	if (log_planner_stats)
 		ShowUsage("PLANNER STATISTICS");
@@ -997,7 +998,7 @@ pg_plan_queries(List *querytrees, const char *query_string, int cursorOptions,
 		else
 		{
 			stmt = pg_plan_query(query, query_string, cursorOptions,
-								 boundParams);
+								 boundParams, NULL);
 		}
 
 		stmt_list = lappend(stmt_list, stmt);
diff --git a/src/include/optimizer/optimizer.h b/src/include/optimizer/optimizer.h
index 04878f1f1c2..a8aaefd27e9 100644
--- a/src/include/optimizer/optimizer.h
+++ b/src/include/optimizer/optimizer.h
@@ -24,6 +24,9 @@
 
 #include "nodes/parsenodes.h"
 
+/* avoid including commands/explain_state.h here */
+struct ExplainState;
+
 /*
  * We don't want to include nodes/pathnodes.h here, because non-planner
  * code should generally treat PlannerInfo as an opaque typedef.
@@ -104,7 +107,8 @@ extern PGDLLIMPORT bool enable_distinct_reordering;
 
 extern PlannedStmt *planner(Query *parse, const char *query_string,
 							int cursorOptions,
-							ParamListInfo boundParams);
+							ParamListInfo boundParams,
+							struct ExplainState *es);
 
 extern Expr *expression_planner(Expr *expr);
 extern Expr *expression_planner_with_deps(Expr *expr,
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index f220e9a270d..6c07711913d 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -22,11 +22,15 @@
 #include "nodes/plannodes.h"
 
 
+/* avoid including commands/explain_state.h here */
+struct ExplainState;
+
 /* Hook for plugins to get control in planner() */
 typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   const char *query_string,
 										   int cursorOptions,
-										   ParamListInfo boundParams);
+										   ParamListInfo boundParams,
+										   struct ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
@@ -40,7 +44,8 @@ extern PGDLLIMPORT create_upper_paths_hook_type create_upper_paths_hook;
 
 extern PlannedStmt *standard_planner(Query *parse, const char *query_string,
 									 int cursorOptions,
-									 ParamListInfo boundParams);
+									 ParamListInfo boundParams,
+									 struct ExplainState *es);
 
 extern PlannerInfo *subquery_planner(PlannerGlobal *glob, Query *parse,
 									 PlannerInfo *parent_root,
diff --git a/src/include/tcop/tcopprot.h b/src/include/tcop/tcopprot.h
index a83cc4f4850..90323b10554 100644
--- a/src/include/tcop/tcopprot.h
+++ b/src/include/tcop/tcopprot.h
@@ -20,6 +20,8 @@
 #include "utils/guc.h"
 #include "utils/queryenvironment.h"
 
+/* avoid including commands/explain_state.h here */
+struct ExplainState;
 
 extern PGDLLIMPORT CommandDest whereToSendOutput;
 extern PGDLLIMPORT const char *debug_query_string;
@@ -63,7 +65,8 @@ extern List *pg_analyze_and_rewrite_withcb(RawStmt *parsetree,
 										   QueryEnvironment *queryEnv);
 extern PlannedStmt *pg_plan_query(Query *querytree, const char *query_string,
 								  int cursorOptions,
-								  ParamListInfo boundParams);
+								  ParamListInfo boundParams,
+								  struct ExplainState *es);
 extern List *pg_plan_queries(List *querytrees, const char *query_string,
 							 int cursorOptions,
 							 ParamListInfo boundParams);
diff --git a/src/test/modules/delay_execution/delay_execution.c b/src/test/modules/delay_execution/delay_execution.c
index 7bc97f84a1c..53c4073fce6 100644
--- a/src/test/modules/delay_execution/delay_execution.c
+++ b/src/test/modules/delay_execution/delay_execution.c
@@ -40,17 +40,18 @@ static planner_hook_type prev_planner_hook = NULL;
 /* planner_hook function to provide the desired delay */
 static PlannedStmt *
 delay_execution_planner(Query *parse, const char *query_string,
-						int cursorOptions, ParamListInfo boundParams)
+						int cursorOptions, ParamListInfo boundParams,
+						struct ExplainState *es)
 {
 	PlannedStmt *result;
 
 	/* Invoke the planner, possibly via a previous hook user */
 	if (prev_planner_hook)
 		result = prev_planner_hook(parse, query_string, cursorOptions,
-								   boundParams);
+								   boundParams, es);
 	else
 		result = standard_planner(parse, query_string, cursorOptions,
-								  boundParams);
+								  boundParams, es);
 
 	/* If enabled, delay by taking and releasing the specified lock */
 	if (post_planning_lock_id != 0)
-- 
2.39.5 (Apple Git-154)

From 747df97779d412f8d5008ed88559ce7242d5e0c1 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 20 Aug 2025 15:10:52 -0400
Subject: [PATCH v4 2/6] Remove PlannerInfo's join_search_private method.

Instead, use the new mechanism that allows planner extensions to store
private state inside a PlannerInfo, treating GEQO as an in-core planner
extension.  This is a useful test of the new facility, and also buys
back a few bytes of storage.

To make this work, we must remove innerrel_is_unique_ext's hack of
testing whether join_search_private is set as a proxy for whether
the join search might be retried. Add a flag that extensions can
use to explicitly signal their intentions instead.
---
 src/backend/optimizer/geqo/geqo_eval.c    |  2 +-
 src/backend/optimizer/geqo/geqo_main.c    | 12 ++++++++++--
 src/backend/optimizer/geqo/geqo_random.c  |  7 +++----
 src/backend/optimizer/plan/analyzejoins.c |  9 +++------
 src/backend/optimizer/plan/planner.c      |  1 +
 src/backend/optimizer/prep/prepjointree.c |  1 +
 src/include/nodes/pathnodes.h             |  5 ++---
 src/include/optimizer/geqo.h              | 10 +++++++++-
 8 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/src/backend/optimizer/geqo/geqo_eval.c b/src/backend/optimizer/geqo/geqo_eval.c
index f07d1dc8ac6..7fcb1aa70d1 100644
--- a/src/backend/optimizer/geqo/geqo_eval.c
+++ b/src/backend/optimizer/geqo/geqo_eval.c
@@ -162,7 +162,7 @@ geqo_eval(PlannerInfo *root, Gene *tour, int num_gene)
 RelOptInfo *
 gimme_tree(PlannerInfo *root, Gene *tour, int num_gene)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 	List	   *clumps;
 	int			rel_count;
 
diff --git a/src/backend/optimizer/geqo/geqo_main.c b/src/backend/optimizer/geqo/geqo_main.c
index 38402ce58db..0064556087a 100644
--- a/src/backend/optimizer/geqo/geqo_main.c
+++ b/src/backend/optimizer/geqo/geqo_main.c
@@ -47,6 +47,8 @@ int			Geqo_generations;
 double		Geqo_selection_bias;
 double		Geqo_seed;
 
+/* GEQO is treated as an in-core planner extension */
+int			Geqo_planner_extension_id = -1;
 
 static int	gimme_pool_size(int nr_rel);
 static int	gimme_number_generations(int pool_size);
@@ -98,10 +100,16 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	int			mutations = 0;
 #endif
 
+	if (Geqo_planner_extension_id < 0)
+		Geqo_planner_extension_id = GetPlannerExtensionId("geqo");
+
 /* set up private information */
-	root->join_search_private = &private;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, &private);
 	private.initial_rels = initial_rels;
 
+/* inform core planner that we may replan */
+	root->assumeReplanning = true;
+
 /* initialize private number generator */
 	geqo_set_seed(root, Geqo_seed);
 
@@ -304,7 +312,7 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	free_pool(root, pool);
 
 	/* ... clear root pointer to our private storage */
-	root->join_search_private = NULL;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, NULL);
 
 	return best_rel;
 }
diff --git a/src/backend/optimizer/geqo/geqo_random.c b/src/backend/optimizer/geqo/geqo_random.c
index 6c7a411f69f..46d28baa2e6 100644
--- a/src/backend/optimizer/geqo/geqo_random.c
+++ b/src/backend/optimizer/geqo/geqo_random.c
@@ -15,11 +15,10 @@
 
 #include "optimizer/geqo_random.h"
 
-
 void
 geqo_set_seed(PlannerInfo *root, double seed)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	pg_prng_fseed(&private->random_state, seed);
 }
@@ -27,7 +26,7 @@ geqo_set_seed(PlannerInfo *root, double seed)
 double
 geqo_rand(PlannerInfo *root)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	return pg_prng_double(&private->random_state);
 }
@@ -35,7 +34,7 @@ geqo_rand(PlannerInfo *root)
 int
 geqo_randint(PlannerInfo *root, int upper, int lower)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	/*
 	 * In current usage, "lower" is never negative so we can just use
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 2a3dea88a94..6a3c030e8ef 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -1425,17 +1425,14 @@ innerrel_is_unique_ext(PlannerInfo *root,
 		 *
 		 * However, in normal planning mode, caching this knowledge is totally
 		 * pointless; it won't be queried again, because we build up joinrels
-		 * from smaller to larger.  It is useful in GEQO mode, where the
-		 * knowledge can be carried across successive planning attempts; and
-		 * it's likely to be useful when using join-search plugins, too. Hence
-		 * cache when join_search_private is non-NULL.  (Yeah, that's a hack,
-		 * but it seems reasonable.)
+		 * from smaller to larger.  It's only useful when using GEQO or
+		 * another planner extension that attempts planning multiple times.
 		 *
 		 * Also, allow callers to override that heuristic and force caching;
 		 * that's useful for reduce_unique_semijoins, which calls here before
 		 * the normal join search starts.
 		 */
-		if (force_cache || root->join_search_private)
+		if (force_cache || root->assumeReplanning)
 		{
 			old_context = MemoryContextSwitchTo(root->planner_cxt);
 			innerrel->non_unique_for_rels =
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 41bd8353430..9de39da1757 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -703,6 +703,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse, PlannerInfo *parent_root,
 	root->hasAlternativeSubPlans = false;
 	root->placeholdersFrozen = false;
 	root->hasRecursion = hasRecursion;
+	root->assumeReplanning = false;
 	if (hasRecursion)
 		root->wt_param_id = assign_special_exec_param(root);
 	else
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 35e8d3c183b..4075f7519ca 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -1383,6 +1383,7 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 	subroot->qual_security_level = 0;
 	subroot->placeholdersFrozen = false;
 	subroot->hasRecursion = false;
+	subroot->assumeReplanning = false;
 	subroot->wt_param_id = -1;
 	subroot->non_recursive_path = NULL;
 	/* We don't currently need a top JoinDomain for the subroot */
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 5cf23cba596..bc1e0c1b5cc 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,8 @@ struct PlannerInfo
 	bool		placeholdersFrozen;
 	/* true if planning a recursive WITH item */
 	bool		hasRecursion;
+	/* true if a planner extension may replan this subquery */
+	bool		assumeReplanning;
 
 	/*
 	 * The rangetable index for the RTE_GROUP RTE, or 0 if there is no
@@ -576,9 +578,6 @@ struct PlannerInfo
 	bool	   *isAltSubplan pg_node_attr(read_write_ignore);
 	bool	   *isUsedSubplan pg_node_attr(read_write_ignore);
 
-	/* optional private data for join_search_hook, e.g., GEQO */
-	void	   *join_search_private pg_node_attr(read_write_ignore);
-
 	/* Does this query modify any partition key columns? */
 	bool		partColsUpdated;
 
diff --git a/src/include/optimizer/geqo.h b/src/include/optimizer/geqo.h
index 9f8e0f337aa..3f4872e25e3 100644
--- a/src/include/optimizer/geqo.h
+++ b/src/include/optimizer/geqo.h
@@ -24,6 +24,7 @@
 
 #include "common/pg_prng.h"
 #include "nodes/pathnodes.h"
+#include "optimizer/extendplan.h"
 #include "optimizer/geqo_gene.h"
 
 
@@ -62,6 +63,8 @@ extern PGDLLIMPORT int Geqo_generations;	/* 1 .. inf, or 0 to use default */
 
 extern PGDLLIMPORT double Geqo_selection_bias;
 
+extern PGDLLIMPORT int Geqo_planner_extension_id;
+
 #define DEFAULT_GEQO_SELECTION_BIAS 2.0
 #define MIN_GEQO_SELECTION_BIAS 1.5
 #define MAX_GEQO_SELECTION_BIAS 2.0
@@ -70,7 +73,7 @@ extern PGDLLIMPORT double Geqo_seed;	/* 0 .. 1 */
 
 
 /*
- * Private state for a GEQO run --- accessible via root->join_search_private
+ * Private state for a GEQO run --- accessible via GetGeqoPrivateData
  */
 typedef struct
 {
@@ -78,6 +81,11 @@ typedef struct
 	pg_prng_state random_state; /* PRNG state */
 } GeqoPrivateData;
 
+static inline GeqoPrivateData *
+GetGeqoPrivateData(PlannerInfo *root)
+{
+	return GetPlannerInfoExtensionState(root, Geqo_planner_extension_id);
+}
 
 /* routines in geqo_main.c */
 extern RelOptInfo *geqo(PlannerInfo *root,
-- 
2.39.5 (Apple Git-154)

From f00ff216cb3c7fe9db7782b22fb3a220edef9589 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 13:04:50 -0400
Subject: [PATCH v4 4/6] Add planner_setup_hook and planner_shutdown_hook.

These hooks allow plugins to get control at the earliest point at
which the PlannerGlobal object is fully initialized, and then just
before it gets destroyed. This is useful in combination with the
extendable plan state facilities (see extendplan.h) and perhaps for
other purposes as well.
---
 src/backend/optimizer/plan/planner.c | 14 ++++++++++++++
 src/include/optimizer/planner.h      | 13 +++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 205d8886a2a..ba69098e0df 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -73,6 +73,12 @@ bool		enable_distinct_reordering = true;
 /* Hook for plugins to get control in planner() */
 planner_hook_type planner_hook = NULL;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+planner_setup_hook_type planner_setup_hook = NULL;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+planner_shutdown_hook_type planner_shutdown_hook = NULL;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 create_upper_paths_hook_type create_upper_paths_hook = NULL;
 
@@ -440,6 +446,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 		tuple_fraction = 0.0;
 	}
 
+	/* Allow plugins to take control after we've initialized "glob" */
+	if (planner_setup_hook)
+		(*planner_setup_hook) (glob, parse, query_string, &tuple_fraction, es);
+
 	/* primary planning entry point (may recurse for subqueries) */
 	root = subquery_planner(glob, parse, NULL, false, tuple_fraction, NULL);
 
@@ -621,6 +631,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 	if (glob->partition_directory != NULL)
 		DestroyPartitionDirectory(glob->partition_directory);
 
+	/* Allow plugins to take control before we discard "glob" */
+	if (planner_shutdown_hook)
+		(*planner_shutdown_hook) (glob, parse, query_string, result);
+
 	return result;
 }
 
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index 6c07711913d..6b893f76444 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -33,6 +33,19 @@ typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   struct ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+typedef void (*planner_setup_hook_type) (PlannerGlobal *glob, Query *parse,
+										 const char *query_string,
+										 double *tuple_fraction,
+										 struct ExplainState *es);
+extern PGDLLIMPORT planner_setup_hook_type planner_setup_hook;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+typedef void (*planner_shutdown_hook_type) (PlannerGlobal *glob, Query *parse,
+											const char *query_string,
+											PlannedStmt *pstmt);
+extern PGDLLIMPORT planner_shutdown_hook_type planner_shutdown_hook;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 typedef void (*create_upper_paths_hook_type) (PlannerInfo *root,
 											  UpperRelationKind stage,
-- 
2.39.5 (Apple Git-154)

From c227de07914c48026838687fc3700f78d1e33329 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 18 Aug 2025 16:11:10 -0400
Subject: [PATCH v4 1/6] Allow private state in certain planner data
 structures.

Extension that make extensive use of planner hooks may want to
coordinate their efforts, for example to avoid duplicate computation,
but that's currently difficult because there's no really good way to
pass data between different hooks.

To make that easier, allow for storage of extension-managed private
state in PlannerGlobal, PlannerInfo, and RelOptInfo, along very
similar lines to what we have permitted for ExplainState since commit
c65bc2e1d14a2d4daed7c1921ac518f2c5ac3d17.
---
 src/backend/optimizer/util/Makefile     |   1 +
 src/backend/optimizer/util/extendplan.c | 181 ++++++++++++++++++++++++
 src/backend/optimizer/util/meson.build  |   1 +
 src/include/nodes/pathnodes.h           |  12 ++
 src/include/optimizer/extendplan.h      |  72 ++++++++++
 5 files changed, 267 insertions(+)
 create mode 100644 src/backend/optimizer/util/extendplan.c
 create mode 100644 src/include/optimizer/extendplan.h

diff --git a/src/backend/optimizer/util/Makefile b/src/backend/optimizer/util/Makefile
index 4fb115cb118..308730f392e 100644
--- a/src/backend/optimizer/util/Makefile
+++ b/src/backend/optimizer/util/Makefile
@@ -14,6 +14,7 @@ include $(top_builddir)/src/Makefile.global
 
 OBJS = \
 	appendinfo.o \
+	extendplan.o \
 	clauses.o \
 	inherit.o \
 	joininfo.o \
diff --git a/src/backend/optimizer/util/extendplan.c b/src/backend/optimizer/util/extendplan.c
new file mode 100644
index 00000000000..55c26cf8411
--- /dev/null
+++ b/src/backend/optimizer/util/extendplan.c
@@ -0,0 +1,181 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.c
+ *	  Extend core planner objects with additional private state
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994-5, Regents of the University of California
+ *
+ * The interfaces defined in this file make it possible for loadable
+ * modules to store their own private state inside of key planner data
+ * structures -- specifically, the PlannerGlobal, PlannerInfo, and
+ * RelOptInfo structures. This can make it much easier to write
+ * reasonably efficient planner extensions; for instance, code that
+ * uses set_join_pathlist_hook can arrange to compute a key intermediate
+ * result once per joinrel rather than on every call.
+ *
+ * IDENTIFICATION
+ *	  src/backend/optimizer/util/extendplan.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "optimizer/extendplan.h"
+#include "port/pg_bitutils.h"
+#include "utils/memutils.h"
+#include "utils/palloc.h"
+
+static const char **PlannerExtensionNameArray = NULL;
+static int	PlannerExtensionNamesAssigned = 0;
+static int	PlannerExtensionNamesAllocated = 0;
+
+/*
+ * Map the name of a planner extension to an integer ID.
+ *
+ * Within the lifetime of a particular backend, the same name will be mapped
+ * to the same ID every time. IDs are not stable across backends. Use the ID
+ * that you get from this function to call the remaining functions in this
+ * file.
+ */
+int
+GetPlannerExtensionId(const char *extension_name)
+{
+	/* Search for an existing extension by this name; if found, return ID. */
+	for (int i = 0; i < PlannerExtensionNamesAssigned; ++i)
+		if (strcmp(PlannerExtensionNameArray[i], extension_name) == 0)
+			return i;
+
+	/* If there is no array yet, create one. */
+	if (PlannerExtensionNameArray == NULL)
+	{
+		PlannerExtensionNamesAllocated = 16;
+		PlannerExtensionNameArray = (const char **)
+			MemoryContextAlloc(TopMemoryContext,
+							   PlannerExtensionNamesAllocated
+							   * sizeof(char *));
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (PlannerExtensionNamesAssigned >= PlannerExtensionNamesAllocated)
+	{
+		int			i = pg_nextpower2_32(PlannerExtensionNamesAssigned + 1);
+
+		PlannerExtensionNameArray = (const char **)
+			repalloc(PlannerExtensionNameArray, i * sizeof(char *));
+		PlannerExtensionNamesAllocated = i;
+	}
+
+	/* Assign and return new ID. */
+	PlannerExtensionNameArray[PlannerExtensionNamesAssigned] = extension_name;
+	return PlannerExtensionNamesAssigned++;
+}
+
+/*
+ * Store extension-specific state into a PlannerGlobal.
+ */
+void
+SetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id,
+							   void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (glob->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(glob);
+		glob->extension_state_allocated = 4;
+		sz = glob->extension_state_allocated * sizeof(void *);
+		glob->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= glob->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(glob->extension_state_allocated + 1);
+		glob->extension_state = (void **)
+			repalloc0(glob->extension_state,
+					  glob->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		glob->extension_state_allocated = i;
+	}
+
+	glob->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a PlannerInfo.
+ */
+void
+SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+							 void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (root->extension_state == NULL)
+	{
+		Size		sz;
+
+		root->extension_state_allocated = 4;
+		sz = root->extension_state_allocated * sizeof(void *);
+		root->extension_state = MemoryContextAllocZero(root->planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= root->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(root->extension_state_allocated + 1);
+		root->extension_state = (void **)
+			repalloc0(root->extension_state,
+					  root->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		root->extension_state_allocated = i;
+	}
+
+	root->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a RelOptInfo.
+ */
+void
+SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+							void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (rel->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(rel);
+		rel->extension_state_allocated = 4;
+		sz = rel->extension_state_allocated * sizeof(void *);
+		rel->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= rel->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(rel->extension_state_allocated + 1);
+		rel->extension_state = (void **)
+			repalloc0(rel->extension_state,
+					  rel->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		rel->extension_state_allocated = i;
+	}
+
+	rel->extension_state[extension_id] = opaque;
+}
diff --git a/src/backend/optimizer/util/meson.build b/src/backend/optimizer/util/meson.build
index b3bf913d096..f71f56e37a1 100644
--- a/src/backend/optimizer/util/meson.build
+++ b/src/backend/optimizer/util/meson.build
@@ -3,6 +3,7 @@
 backend_sources += files(
   'appendinfo.c',
   'clauses.c',
+  'extendplan.c',
   'inherit.c',
   'joininfo.c',
   'orclauses.c',
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index b12a2508d8c..5cf23cba596 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -182,6 +182,10 @@ typedef struct PlannerGlobal
 
 	/* hash table for NOT NULL attnums of relations */
 	struct HTAB *rel_notnullatts_hash pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } PlannerGlobal;
 
 /* macro for fetching the Plan associated with a SubPlan node */
@@ -580,6 +584,10 @@ struct PlannerInfo
 
 	/* PartitionPruneInfos added in this query's plan. */
 	List	   *partPruneInfos;
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 };
 
 
@@ -1091,6 +1099,10 @@ typedef struct RelOptInfo
 	List	  **partexprs pg_node_attr(read_write_ignore);
 	/* Nullable partition key expressions */
 	List	  **nullable_partexprs pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } RelOptInfo;
 
 /*
diff --git a/src/include/optimizer/extendplan.h b/src/include/optimizer/extendplan.h
new file mode 100644
index 00000000000..de9618761dd
--- /dev/null
+++ b/src/include/optimizer/extendplan.h
@@ -0,0 +1,72 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.h
+ *	  Extend core planner objects with additional private state
+ *
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/optimizer/extendplan.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef EXTENDPLAN_H
+#define EXTENDPLAN_H
+
+#include "nodes/pathnodes.h"
+
+extern int	GetPlannerExtensionId(const char *extension_name);
+
+/*
+ * Get extension-specific state from a PlannerGlobal.
+ */
+static inline void *
+GetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= glob->extension_state_allocated)
+		return NULL;
+
+	return glob->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetPlannerInfoExtensionState(PlannerInfo *root, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= root->extension_state_allocated)
+		return NULL;
+
+	return root->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= rel->extension_state_allocated)
+		return NULL;
+
+	return rel->extension_state[extension_id];
+}
+
+/* Functions to store private state into various planner objects */
+extern void SetPlannerGlobalExtensionState(PlannerGlobal *glob,
+										   int extension_id,
+										   void *opaque);
+extern void SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+										 void *opaque);
+extern void SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+										void *opaque);
+
+#endif
-- 
2.39.5 (Apple Git-154)

From a9757078ede132a93a746eece0b0b605b19fb8af Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 14:29:02 -0400
Subject: [PATCH v4 5/6] Add extension_state member to PlannedStmt.

Extensions can stash data computed at plan time into this list using
planner_shutdown_hook (or perhaps other mechanisms) and then access
it from any code that has access to the PlannedStmt (such as explain
hooks), allowing for extensible debugging and instrumentation of
plans.
---
 src/include/nodes/plannodes.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 3908847e3bf..afc00228396 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -149,6 +149,15 @@ typedef struct PlannedStmt
 	/* non-null if this is utility stmt */
 	Node	   *utilityStmt;
 
+	/*
+	 * DefElem objects added by extensions, e.g. using planner_shutdown_hook
+	 *
+	 * Set each DefElem's defname to the name of the plugin or extension, and
+	 * the argument to a tree of nodes that all have copy and read/write
+	 * support.
+	 */
+	List	   *extension_state;
+
 	/* statement location in source string (copied from Query) */
 	/* start location, or -1 if unknown */
 	ParseLoc	stmt_location;
-- 
2.39.5 (Apple Git-154)

From 6291ca3a75fefad7578294e5b7976cb8d503186c Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 15:22:57 -0400
Subject: [PATCH v4 6/6] not for commit: count distinct joinrels and joinrel
 planning attempts

---
 .../expected/pg_overexplain.out               |  22 ++-
 contrib/pg_overexplain/pg_overexplain.c       | 125 ++++++++++++++++++
 2 files changed, 142 insertions(+), 5 deletions(-)

diff --git a/contrib/pg_overexplain/expected/pg_overexplain.out b/contrib/pg_overexplain/expected/pg_overexplain.out
index 55d34666d87..48251298f05 100644
--- a/contrib/pg_overexplain/expected/pg_overexplain.out
+++ b/contrib/pg_overexplain/expected/pg_overexplain.out
@@ -38,7 +38,9 @@ EXPLAIN (DEBUG) SELECT 1;
    Relation OIDs: none
    Executor Parameter Types: none
    Parse Location: 0 to end
-(11 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(13 rows)
 
 EXPLAIN (RANGE_TABLE) SELECT 1;
                 QUERY PLAN                
@@ -121,6 +123,8 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
  RTI 1 (relation, inherited, in-from-clause):
    Eref: vegetables (id, name, genus)
    Relation: vegetables
@@ -142,7 +146,7 @@ $$);
    Relation Kind: relation
    Relation Lock Mode: AccessShareLock
  Unprunable RTIs: 1 3 4
-(53 rows)
+(55 rows)
 
 -- Test a different output format.
 SELECT explain_filter($$
@@ -242,6 +246,8 @@ $$);
        <Relation-OIDs>NNN...</Relation-OIDs>                        +
        <Executor-Parameter-Types>none</Executor-Parameter-Types>    +
        <Parse-Location>0 to end</Parse-Location>                    +
+       <Total-Joinrel-Attempts>0</Total-Joinrel-Attempts>           +
+       <Distinct-Joinrels>0</Distinct-Joinrels>                     +
      </PlannedStmt>                                                 +
      <Range-Table>                                                  +
        <Range-Table-Entry>                                          +
@@ -346,7 +352,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
-(37 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(39 rows)
 
 SET debug_parallel_query = false;
 RESET enable_seqscan;
@@ -374,7 +382,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 0
    Parse Location: 0 to end
-(15 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(17 rows)
 
 -- Create an index, and then attempt to force a nested loop with inner index
 -- scan so that we can see parameter-related information. Also, let's try
@@ -438,7 +448,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 23
    Parse Location: 0 to end
-(47 rows)
+   Total Joinrel Attempts: 2
+   Distinct Joinrels: 1
+(49 rows)
 
 RESET enable_hashjoin;
 RESET enable_material;
diff --git a/contrib/pg_overexplain/pg_overexplain.c b/contrib/pg_overexplain/pg_overexplain.c
index bd70b6d9d5e..93d2051f4fb 100644
--- a/contrib/pg_overexplain/pg_overexplain.c
+++ b/contrib/pg_overexplain/pg_overexplain.c
@@ -16,6 +16,10 @@
 #include "commands/explain_format.h"
 #include "commands/explain_state.h"
 #include "fmgr.h"
+#include "nodes/makefuncs.h"
+#include "optimizer/extendplan.h"
+#include "optimizer/paths.h"
+#include "optimizer/planner.h"
 #include "parser/parsetree.h"
 #include "storage/lock.h"
 #include "utils/builtins.h"
@@ -32,6 +36,12 @@ typedef struct
 	bool		range_table;
 } overexplain_options;
 
+typedef struct
+{
+	int			total_joinrel_attempts;
+	int			distinct_joinrel_count;
+} overexplain_plannerglobal;
+
 static overexplain_options *overexplain_ensure_options(ExplainState *es);
 static void overexplain_debug_handler(ExplainState *es, DefElem *opt,
 									  ParseState *pstate);
@@ -57,9 +67,28 @@ static void overexplain_bitmapset(const char *qlabel, Bitmapset *bms,
 static void overexplain_intlist(const char *qlabel, List *list,
 								ExplainState *es);
 
+static void overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+										   const char *query_string,
+										   double *tuple_fraction,
+										   struct ExplainState *es);
+static void overexplain_planner_shutdown_hook(PlannerGlobal *glob,
+											  Query *parse,
+											  const char *query_string,
+											  PlannedStmt *pstmt);
+static void overexplain_set_join_pathlist_hook(PlannerInfo *root,
+											   RelOptInfo *joinrel,
+											   RelOptInfo *outerrel,
+											   RelOptInfo *innerrel,
+											   JoinType jointype,
+											   JoinPathExtraData *extra);
+
 static int	es_extension_id;
+static int	planner_extension_id = -1;
 static explain_per_node_hook_type prev_explain_per_node_hook;
 static explain_per_plan_hook_type prev_explain_per_plan_hook;
+static planner_setup_hook_type prev_planner_setup_hook;
+static planner_shutdown_hook_type prev_planner_shutdown_hook;
+static set_join_pathlist_hook_type prev_set_join_pathlist_hook;
 
 /*
  * Initialization we do when this module is loaded.
@@ -70,6 +99,9 @@ _PG_init(void)
 	/* Get an ID that we can use to cache data in an ExplainState. */
 	es_extension_id = GetExplainExtensionId("pg_overexplain");
 
+	/* Get an ID that we can use to cache data in the planner. */
+	planner_extension_id = GetPlannerExtensionId("pg_overexplain");
+
 	/* Register the new EXPLAIN options implemented by this module. */
 	RegisterExtensionExplainOption("debug", overexplain_debug_handler);
 	RegisterExtensionExplainOption("range_table",
@@ -80,6 +112,16 @@ _PG_init(void)
 	explain_per_node_hook = overexplain_per_node_hook;
 	prev_explain_per_plan_hook = explain_per_plan_hook;
 	explain_per_plan_hook = overexplain_per_plan_hook;
+
+	/* Example of planner_setup_hook/planner_shutdown_hook use */
+	prev_planner_setup_hook = planner_setup_hook;
+	planner_setup_hook = overexplain_planner_setup_hook;
+	prev_planner_shutdown_hook = planner_shutdown_hook;
+	planner_shutdown_hook = overexplain_planner_shutdown_hook;
+
+	/* Support for above example */
+	prev_set_join_pathlist_hook = set_join_pathlist_hook;
+	set_join_pathlist_hook = overexplain_set_join_pathlist_hook;
 }
 
 /*
@@ -381,6 +423,29 @@ overexplain_debug(PlannedStmt *plannedstmt, ExplainState *es)
 									 plannedstmt->stmt_len),
 							es);
 
+	{
+		DefElem    *elem = NULL;
+
+		foreach_node(DefElem, de, plannedstmt->extension_state)
+		{
+			if (strcmp(de->defname, "pg_overexplain") == 0)
+			{
+				elem = de;
+				break;
+			}
+		}
+
+		if (elem != NULL)
+		{
+			List	   *l = castNode(List, elem->arg);
+
+			ExplainPropertyInteger("Total Joinrel Attempts", NULL,
+								   intVal(linitial(l)), es);
+			ExplainPropertyInteger("Distinct Joinrels", NULL,
+								   intVal(lsecond(l)), es);
+		}
+	}
+
 	/* Done with this group. */
 	if (es->format == EXPLAIN_FORMAT_TEXT)
 		es->indent--;
@@ -784,3 +849,63 @@ overexplain_intlist(const char *qlabel, List *list, ExplainState *es)
 
 	pfree(buf.data);
 }
+
+static void
+overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+							   const char *query_string,
+							   double *tuple_fraction,
+							   struct ExplainState *es)
+{
+	overexplain_options *options;
+	overexplain_plannerglobal *g;
+
+	if (es != NULL)
+	{
+		options = GetExplainExtensionState(es, es_extension_id);
+		if (options != NULL && options->debug)
+		{
+			g = palloc0_object(overexplain_plannerglobal);
+			SetPlannerGlobalExtensionState(glob, planner_extension_id, g);
+		}
+	}
+}
+
+static void
+overexplain_planner_shutdown_hook(PlannerGlobal *glob, Query *parse,
+								  const char *query_string, PlannedStmt *pstmt)
+{
+	overexplain_plannerglobal *g;
+	DefElem    *elem;
+	List	   *l;
+
+	g = GetPlannerGlobalExtensionState(glob, planner_extension_id);
+	if (g != NULL)
+	{
+		l = list_make2(makeInteger(g->total_joinrel_attempts),
+					   makeInteger(g->distinct_joinrel_count));
+		elem = makeDefElem("pg_overexplain", (Node *) l, -1);
+		pstmt->extension_state = lappend(pstmt->extension_state, elem);
+	}
+}
+
+static void
+overexplain_set_join_pathlist_hook(PlannerInfo *root, RelOptInfo *joinrel,
+								   RelOptInfo *outerrel, RelOptInfo *innerrel,
+								   JoinType jointype, JoinPathExtraData *extra)
+{
+	overexplain_plannerglobal *g;
+
+	g = GetPlannerGlobalExtensionState(root->glob, planner_extension_id);
+
+	if (g != NULL)
+	{
+		g->total_joinrel_attempts++;
+
+		if (GetRelOptInfoExtensionState(joinrel, planner_extension_id) == NULL)
+		{
+			g->distinct_joinrel_count++;
+			/* set any non-NULL value to avoid double-counting */
+			SetRelOptInfoExtensionState(joinrel, planner_extension_id, g);
+		}
+	}
+}
-- 
2.39.5 (Apple Git-154)

From f364769028ba4b0b2ea5c4ab0ff51ff004c3c547 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 18 Aug 2025 16:11:10 -0400
Subject: [PATCH v5 1/6] Allow private state in certain planner data
 structures.

Extension that make extensive use of planner hooks may want to
coordinate their efforts, for example to avoid duplicate computation,
but that's currently difficult because there's no really good way to
pass data between different hooks.

To make that easier, allow for storage of extension-managed private
state in PlannerGlobal, PlannerInfo, and RelOptInfo, along very
similar lines to what we have permitted for ExplainState since commit
c65bc2e1d14a2d4daed7c1921ac518f2c5ac3d17.
---
 src/backend/optimizer/util/Makefile     |   1 +
 src/backend/optimizer/util/extendplan.c | 181 ++++++++++++++++++++++++
 src/backend/optimizer/util/meson.build  |   1 +
 src/include/nodes/pathnodes.h           |  12 ++
 src/include/optimizer/extendplan.h      |  72 ++++++++++
 5 files changed, 267 insertions(+)
 create mode 100644 src/backend/optimizer/util/extendplan.c
 create mode 100644 src/include/optimizer/extendplan.h

diff --git a/src/backend/optimizer/util/Makefile b/src/backend/optimizer/util/Makefile
index 4fb115cb118..308730f392e 100644
--- a/src/backend/optimizer/util/Makefile
+++ b/src/backend/optimizer/util/Makefile
@@ -14,6 +14,7 @@ include $(top_builddir)/src/Makefile.global
 
 OBJS = \
 	appendinfo.o \
+	extendplan.o \
 	clauses.o \
 	inherit.o \
 	joininfo.o \
diff --git a/src/backend/optimizer/util/extendplan.c b/src/backend/optimizer/util/extendplan.c
new file mode 100644
index 00000000000..55c26cf8411
--- /dev/null
+++ b/src/backend/optimizer/util/extendplan.c
@@ -0,0 +1,181 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.c
+ *	  Extend core planner objects with additional private state
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994-5, Regents of the University of California
+ *
+ * The interfaces defined in this file make it possible for loadable
+ * modules to store their own private state inside of key planner data
+ * structures -- specifically, the PlannerGlobal, PlannerInfo, and
+ * RelOptInfo structures. This can make it much easier to write
+ * reasonably efficient planner extensions; for instance, code that
+ * uses set_join_pathlist_hook can arrange to compute a key intermediate
+ * result once per joinrel rather than on every call.
+ *
+ * IDENTIFICATION
+ *	  src/backend/optimizer/util/extendplan.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "optimizer/extendplan.h"
+#include "port/pg_bitutils.h"
+#include "utils/memutils.h"
+#include "utils/palloc.h"
+
+static const char **PlannerExtensionNameArray = NULL;
+static int	PlannerExtensionNamesAssigned = 0;
+static int	PlannerExtensionNamesAllocated = 0;
+
+/*
+ * Map the name of a planner extension to an integer ID.
+ *
+ * Within the lifetime of a particular backend, the same name will be mapped
+ * to the same ID every time. IDs are not stable across backends. Use the ID
+ * that you get from this function to call the remaining functions in this
+ * file.
+ */
+int
+GetPlannerExtensionId(const char *extension_name)
+{
+	/* Search for an existing extension by this name; if found, return ID. */
+	for (int i = 0; i < PlannerExtensionNamesAssigned; ++i)
+		if (strcmp(PlannerExtensionNameArray[i], extension_name) == 0)
+			return i;
+
+	/* If there is no array yet, create one. */
+	if (PlannerExtensionNameArray == NULL)
+	{
+		PlannerExtensionNamesAllocated = 16;
+		PlannerExtensionNameArray = (const char **)
+			MemoryContextAlloc(TopMemoryContext,
+							   PlannerExtensionNamesAllocated
+							   * sizeof(char *));
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (PlannerExtensionNamesAssigned >= PlannerExtensionNamesAllocated)
+	{
+		int			i = pg_nextpower2_32(PlannerExtensionNamesAssigned + 1);
+
+		PlannerExtensionNameArray = (const char **)
+			repalloc(PlannerExtensionNameArray, i * sizeof(char *));
+		PlannerExtensionNamesAllocated = i;
+	}
+
+	/* Assign and return new ID. */
+	PlannerExtensionNameArray[PlannerExtensionNamesAssigned] = extension_name;
+	return PlannerExtensionNamesAssigned++;
+}
+
+/*
+ * Store extension-specific state into a PlannerGlobal.
+ */
+void
+SetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id,
+							   void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (glob->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(glob);
+		glob->extension_state_allocated = 4;
+		sz = glob->extension_state_allocated * sizeof(void *);
+		glob->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= glob->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(glob->extension_state_allocated + 1);
+		glob->extension_state = (void **)
+			repalloc0(glob->extension_state,
+					  glob->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		glob->extension_state_allocated = i;
+	}
+
+	glob->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a PlannerInfo.
+ */
+void
+SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+							 void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (root->extension_state == NULL)
+	{
+		Size		sz;
+
+		root->extension_state_allocated = 4;
+		sz = root->extension_state_allocated * sizeof(void *);
+		root->extension_state = MemoryContextAllocZero(root->planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= root->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(root->extension_state_allocated + 1);
+		root->extension_state = (void **)
+			repalloc0(root->extension_state,
+					  root->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		root->extension_state_allocated = i;
+	}
+
+	root->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a RelOptInfo.
+ */
+void
+SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+							void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (rel->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(rel);
+		rel->extension_state_allocated = 4;
+		sz = rel->extension_state_allocated * sizeof(void *);
+		rel->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= rel->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(rel->extension_state_allocated + 1);
+		rel->extension_state = (void **)
+			repalloc0(rel->extension_state,
+					  rel->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		rel->extension_state_allocated = i;
+	}
+
+	rel->extension_state[extension_id] = opaque;
+}
diff --git a/src/backend/optimizer/util/meson.build b/src/backend/optimizer/util/meson.build
index b3bf913d096..f71f56e37a1 100644
--- a/src/backend/optimizer/util/meson.build
+++ b/src/backend/optimizer/util/meson.build
@@ -3,6 +3,7 @@
 backend_sources += files(
   'appendinfo.c',
   'clauses.c',
+  'extendplan.c',
   'inherit.c',
   'joininfo.c',
   'orclauses.c',
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index b12a2508d8c..5cf23cba596 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -182,6 +182,10 @@ typedef struct PlannerGlobal
 
 	/* hash table for NOT NULL attnums of relations */
 	struct HTAB *rel_notnullatts_hash pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } PlannerGlobal;
 
 /* macro for fetching the Plan associated with a SubPlan node */
@@ -580,6 +584,10 @@ struct PlannerInfo
 
 	/* PartitionPruneInfos added in this query's plan. */
 	List	   *partPruneInfos;
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 };
 
 
@@ -1091,6 +1099,10 @@ typedef struct RelOptInfo
 	List	  **partexprs pg_node_attr(read_write_ignore);
 	/* Nullable partition key expressions */
 	List	  **nullable_partexprs pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } RelOptInfo;
 
 /*
diff --git a/src/include/optimizer/extendplan.h b/src/include/optimizer/extendplan.h
new file mode 100644
index 00000000000..de9618761dd
--- /dev/null
+++ b/src/include/optimizer/extendplan.h
@@ -0,0 +1,72 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.h
+ *	  Extend core planner objects with additional private state
+ *
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/optimizer/extendplan.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef EXTENDPLAN_H
+#define EXTENDPLAN_H
+
+#include "nodes/pathnodes.h"
+
+extern int	GetPlannerExtensionId(const char *extension_name);
+
+/*
+ * Get extension-specific state from a PlannerGlobal.
+ */
+static inline void *
+GetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= glob->extension_state_allocated)
+		return NULL;
+
+	return glob->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetPlannerInfoExtensionState(PlannerInfo *root, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= root->extension_state_allocated)
+		return NULL;
+
+	return root->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= rel->extension_state_allocated)
+		return NULL;
+
+	return rel->extension_state[extension_id];
+}
+
+/* Functions to store private state into various planner objects */
+extern void SetPlannerGlobalExtensionState(PlannerGlobal *glob,
+										   int extension_id,
+										   void *opaque);
+extern void SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+										 void *opaque);
+extern void SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+										void *opaque);
+
+#endif
-- 
2.39.5 (Apple Git-154)

From 0f3e44ab990436bedf74fcaede4105efbb976b5c Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 14:29:02 -0400
Subject: [PATCH v5 5/6] Add extension_state member to PlannedStmt.

Extensions can stash data computed at plan time into this list using
planner_shutdown_hook (or perhaps other mechanisms) and then access
it from any code that has access to the PlannedStmt (such as explain
hooks), allowing for extensible debugging and instrumentation of
plans.
---
 src/include/nodes/plannodes.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 29d7732d6a0..326c3f7fe6f 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -149,6 +149,15 @@ typedef struct PlannedStmt
 	/* non-null if this is utility stmt */
 	Node	   *utilityStmt;
 
+	/*
+	 * DefElem objects added by extensions, e.g. using planner_shutdown_hook
+	 *
+	 * Set each DefElem's defname to the name of the plugin or extension, and
+	 * the argument to a tree of nodes that all have copy and read/write
+	 * support.
+	 */
+	List	   *extension_state;
+
 	/* statement location in source string (copied from Query) */
 	/* start location, or -1 if unknown */
 	ParseLoc	stmt_location;
-- 
2.39.5 (Apple Git-154)

From eb88b611b936780db66bd66afbd56a9793a07e25 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 20 Aug 2025 15:10:52 -0400
Subject: [PATCH v5 2/6] Remove PlannerInfo's join_search_private method.

Instead, use the new mechanism that allows planner extensions to store
private state inside a PlannerInfo, treating GEQO as an in-core planner
extension.  This is a useful test of the new facility, and also buys
back a few bytes of storage.

To make this work, we must remove innerrel_is_unique_ext's hack of
testing whether join_search_private is set as a proxy for whether
the join search might be retried. Add a flag that extensions can
use to explicitly signal their intentions instead.
---
 src/backend/optimizer/geqo/geqo_eval.c    |  2 +-
 src/backend/optimizer/geqo/geqo_main.c    | 12 ++++++++++--
 src/backend/optimizer/geqo/geqo_random.c  |  7 +++----
 src/backend/optimizer/plan/analyzejoins.c |  9 +++------
 src/backend/optimizer/plan/planner.c      |  1 +
 src/backend/optimizer/prep/prepjointree.c |  1 +
 src/include/nodes/pathnodes.h             |  5 ++---
 src/include/optimizer/geqo.h              | 10 +++++++++-
 8 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/src/backend/optimizer/geqo/geqo_eval.c b/src/backend/optimizer/geqo/geqo_eval.c
index f07d1dc8ac6..7fcb1aa70d1 100644
--- a/src/backend/optimizer/geqo/geqo_eval.c
+++ b/src/backend/optimizer/geqo/geqo_eval.c
@@ -162,7 +162,7 @@ geqo_eval(PlannerInfo *root, Gene *tour, int num_gene)
 RelOptInfo *
 gimme_tree(PlannerInfo *root, Gene *tour, int num_gene)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 	List	   *clumps;
 	int			rel_count;
 
diff --git a/src/backend/optimizer/geqo/geqo_main.c b/src/backend/optimizer/geqo/geqo_main.c
index 38402ce58db..0064556087a 100644
--- a/src/backend/optimizer/geqo/geqo_main.c
+++ b/src/backend/optimizer/geqo/geqo_main.c
@@ -47,6 +47,8 @@ int			Geqo_generations;
 double		Geqo_selection_bias;
 double		Geqo_seed;
 
+/* GEQO is treated as an in-core planner extension */
+int			Geqo_planner_extension_id = -1;
 
 static int	gimme_pool_size(int nr_rel);
 static int	gimme_number_generations(int pool_size);
@@ -98,10 +100,16 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	int			mutations = 0;
 #endif
 
+	if (Geqo_planner_extension_id < 0)
+		Geqo_planner_extension_id = GetPlannerExtensionId("geqo");
+
 /* set up private information */
-	root->join_search_private = &private;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, &private);
 	private.initial_rels = initial_rels;
 
+/* inform core planner that we may replan */
+	root->assumeReplanning = true;
+
 /* initialize private number generator */
 	geqo_set_seed(root, Geqo_seed);
 
@@ -304,7 +312,7 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	free_pool(root, pool);
 
 	/* ... clear root pointer to our private storage */
-	root->join_search_private = NULL;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, NULL);
 
 	return best_rel;
 }
diff --git a/src/backend/optimizer/geqo/geqo_random.c b/src/backend/optimizer/geqo/geqo_random.c
index 6c7a411f69f..46d28baa2e6 100644
--- a/src/backend/optimizer/geqo/geqo_random.c
+++ b/src/backend/optimizer/geqo/geqo_random.c
@@ -15,11 +15,10 @@
 
 #include "optimizer/geqo_random.h"
 
-
 void
 geqo_set_seed(PlannerInfo *root, double seed)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	pg_prng_fseed(&private->random_state, seed);
 }
@@ -27,7 +26,7 @@ geqo_set_seed(PlannerInfo *root, double seed)
 double
 geqo_rand(PlannerInfo *root)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	return pg_prng_double(&private->random_state);
 }
@@ -35,7 +34,7 @@ geqo_rand(PlannerInfo *root)
 int
 geqo_randint(PlannerInfo *root, int upper, int lower)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	/*
 	 * In current usage, "lower" is never negative so we can just use
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 2a3dea88a94..6a3c030e8ef 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -1425,17 +1425,14 @@ innerrel_is_unique_ext(PlannerInfo *root,
 		 *
 		 * However, in normal planning mode, caching this knowledge is totally
 		 * pointless; it won't be queried again, because we build up joinrels
-		 * from smaller to larger.  It is useful in GEQO mode, where the
-		 * knowledge can be carried across successive planning attempts; and
-		 * it's likely to be useful when using join-search plugins, too. Hence
-		 * cache when join_search_private is non-NULL.  (Yeah, that's a hack,
-		 * but it seems reasonable.)
+		 * from smaller to larger.  It's only useful when using GEQO or
+		 * another planner extension that attempts planning multiple times.
 		 *
 		 * Also, allow callers to override that heuristic and force caching;
 		 * that's useful for reduce_unique_semijoins, which calls here before
 		 * the normal join search starts.
 		 */
-		if (force_cache || root->join_search_private)
+		if (force_cache || root->assumeReplanning)
 		{
 			old_context = MemoryContextSwitchTo(root->planner_cxt);
 			innerrel->non_unique_for_rels =
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 41bd8353430..9de39da1757 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -703,6 +703,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse, PlannerInfo *parent_root,
 	root->hasAlternativeSubPlans = false;
 	root->placeholdersFrozen = false;
 	root->hasRecursion = hasRecursion;
+	root->assumeReplanning = false;
 	if (hasRecursion)
 		root->wt_param_id = assign_special_exec_param(root);
 	else
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 35e8d3c183b..4075f7519ca 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -1383,6 +1383,7 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 	subroot->qual_security_level = 0;
 	subroot->placeholdersFrozen = false;
 	subroot->hasRecursion = false;
+	subroot->assumeReplanning = false;
 	subroot->wt_param_id = -1;
 	subroot->non_recursive_path = NULL;
 	/* We don't currently need a top JoinDomain for the subroot */
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 5cf23cba596..bc1e0c1b5cc 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,8 @@ struct PlannerInfo
 	bool		placeholdersFrozen;
 	/* true if planning a recursive WITH item */
 	bool		hasRecursion;
+	/* true if a planner extension may replan this subquery */
+	bool		assumeReplanning;
 
 	/*
 	 * The rangetable index for the RTE_GROUP RTE, or 0 if there is no
@@ -576,9 +578,6 @@ struct PlannerInfo
 	bool	   *isAltSubplan pg_node_attr(read_write_ignore);
 	bool	   *isUsedSubplan pg_node_attr(read_write_ignore);
 
-	/* optional private data for join_search_hook, e.g., GEQO */
-	void	   *join_search_private pg_node_attr(read_write_ignore);
-
 	/* Does this query modify any partition key columns? */
 	bool		partColsUpdated;
 
diff --git a/src/include/optimizer/geqo.h b/src/include/optimizer/geqo.h
index 9f8e0f337aa..3f4872e25e3 100644
--- a/src/include/optimizer/geqo.h
+++ b/src/include/optimizer/geqo.h
@@ -24,6 +24,7 @@
 
 #include "common/pg_prng.h"
 #include "nodes/pathnodes.h"
+#include "optimizer/extendplan.h"
 #include "optimizer/geqo_gene.h"
 
 
@@ -62,6 +63,8 @@ extern PGDLLIMPORT int Geqo_generations;	/* 1 .. inf, or 0 to use default */
 
 extern PGDLLIMPORT double Geqo_selection_bias;
 
+extern PGDLLIMPORT int Geqo_planner_extension_id;
+
 #define DEFAULT_GEQO_SELECTION_BIAS 2.0
 #define MIN_GEQO_SELECTION_BIAS 1.5
 #define MAX_GEQO_SELECTION_BIAS 2.0
@@ -70,7 +73,7 @@ extern PGDLLIMPORT double Geqo_seed;	/* 0 .. 1 */
 
 
 /*
- * Private state for a GEQO run --- accessible via root->join_search_private
+ * Private state for a GEQO run --- accessible via GetGeqoPrivateData
  */
 typedef struct
 {
@@ -78,6 +81,11 @@ typedef struct
 	pg_prng_state random_state; /* PRNG state */
 } GeqoPrivateData;
 
+static inline GeqoPrivateData *
+GetGeqoPrivateData(PlannerInfo *root)
+{
+	return GetPlannerInfoExtensionState(root, Geqo_planner_extension_id);
+}
 
 /* routines in geqo_main.c */
 extern RelOptInfo *geqo(PlannerInfo *root,
-- 
2.39.5 (Apple Git-154)

From ec8779119aeccc560f2c891102f559814a3a3963 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 13:04:50 -0400
Subject: [PATCH v5 4/6] Add planner_setup_hook and planner_shutdown_hook.

These hooks allow plugins to get control at the earliest point at
which the PlannerGlobal object is fully initialized, and then just
before it gets destroyed. This is useful in combination with the
extendable plan state facilities (see extendplan.h) and perhaps for
other purposes as well.
---
 src/backend/optimizer/plan/planner.c | 14 ++++++++++++++
 src/include/optimizer/planner.h      | 13 +++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 205d8886a2a..ba69098e0df 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -73,6 +73,12 @@ bool		enable_distinct_reordering = true;
 /* Hook for plugins to get control in planner() */
 planner_hook_type planner_hook = NULL;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+planner_setup_hook_type planner_setup_hook = NULL;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+planner_shutdown_hook_type planner_shutdown_hook = NULL;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 create_upper_paths_hook_type create_upper_paths_hook = NULL;
 
@@ -440,6 +446,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 		tuple_fraction = 0.0;
 	}
 
+	/* Allow plugins to take control after we've initialized "glob" */
+	if (planner_setup_hook)
+		(*planner_setup_hook) (glob, parse, query_string, &tuple_fraction, es);
+
 	/* primary planning entry point (may recurse for subqueries) */
 	root = subquery_planner(glob, parse, NULL, false, tuple_fraction, NULL);
 
@@ -621,6 +631,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 	if (glob->partition_directory != NULL)
 		DestroyPartitionDirectory(glob->partition_directory);
 
+	/* Allow plugins to take control before we discard "glob" */
+	if (planner_shutdown_hook)
+		(*planner_shutdown_hook) (glob, parse, query_string, result);
+
 	return result;
 }
 
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index 6c07711913d..6b893f76444 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -33,6 +33,19 @@ typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   struct ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+typedef void (*planner_setup_hook_type) (PlannerGlobal *glob, Query *parse,
+										 const char *query_string,
+										 double *tuple_fraction,
+										 struct ExplainState *es);
+extern PGDLLIMPORT planner_setup_hook_type planner_setup_hook;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+typedef void (*planner_shutdown_hook_type) (PlannerGlobal *glob, Query *parse,
+											const char *query_string,
+											PlannedStmt *pstmt);
+extern PGDLLIMPORT planner_shutdown_hook_type planner_shutdown_hook;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 typedef void (*create_upper_paths_hook_type) (PlannerInfo *root,
 											  UpperRelationKind stage,
-- 
2.39.5 (Apple Git-154)

From d54722ba6e94aebe142be25055f73dfdc002654a Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 16 Sep 2025 13:13:24 -0400
Subject: [PATCH v5 3/6] Add ExplainState argument to pg_plan_query() and
 planner().

This allows extensions to have access to any data they've stored
in the ExplainState during planning. Unfortunately, it won't help
with EXPLAIN EXECUTE is used, but since that case is less common,
this still seems like an improvement.
---
 contrib/pg_stat_statements/pg_stat_statements.c    | 14 ++++++++------
 src/backend/commands/copyto.c                      |  2 +-
 src/backend/commands/createas.c                    |  2 +-
 src/backend/commands/explain.c                     |  2 +-
 src/backend/commands/matview.c                     |  2 +-
 src/backend/commands/portalcmds.c                  |  3 ++-
 src/backend/optimizer/plan/planner.c               | 10 ++++++----
 src/backend/tcop/postgres.c                        |  7 ++++---
 src/include/optimizer/optimizer.h                  |  6 +++++-
 src/include/optimizer/planner.h                    |  9 +++++++--
 src/include/tcop/tcopprot.h                        |  5 ++++-
 src/test/modules/delay_execution/delay_execution.c |  7 ++++---
 12 files changed, 44 insertions(+), 25 deletions(-)

diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 0bb0f933399..0eb208f58fc 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -337,7 +337,8 @@ static void pgss_post_parse_analyze(ParseState *pstate, Query *query,
 static PlannedStmt *pgss_planner(Query *parse,
 								 const char *query_string,
 								 int cursorOptions,
-								 ParamListInfo boundParams);
+								 ParamListInfo boundParams,
+								 struct ExplainState *es);
 static void pgss_ExecutorStart(QueryDesc *queryDesc, int eflags);
 static void pgss_ExecutorRun(QueryDesc *queryDesc,
 							 ScanDirection direction,
@@ -893,7 +894,8 @@ static PlannedStmt *
 pgss_planner(Query *parse,
 			 const char *query_string,
 			 int cursorOptions,
-			 ParamListInfo boundParams)
+			 ParamListInfo boundParams,
+			 struct ExplainState *es)
 {
 	PlannedStmt *result;
 
@@ -928,10 +930,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
@@ -977,10 +979,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
diff --git a/src/backend/commands/copyto.c b/src/backend/commands/copyto.c
index 67b94b91cae..e5781155cdf 100644
--- a/src/backend/commands/copyto.c
+++ b/src/backend/commands/copyto.c
@@ -796,7 +796,7 @@ BeginCopyTo(ParseState *pstate,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, NULL);
+							 CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 		/*
 		 * With row-level security and a user using "COPY relation TO", we
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1ccc2e55c64 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -321,7 +321,7 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, params);
+							 CURSOR_OPT_PARALLEL_OK, params, NULL);
 
 		/*
 		 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 8345bc0264b..ca64fa5d18a 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -350,7 +350,7 @@ standard_ExplainOneQuery(Query *query, int cursorOptions,
 	INSTR_TIME_SET_CURRENT(planstart);
 
 	/* plan the query */
-	plan = pg_plan_query(query, queryString, cursorOptions, params);
+	plan = pg_plan_query(query, queryString, cursorOptions, params, es);
 
 	INSTR_TIME_SET_CURRENT(planduration);
 	INSTR_TIME_SUBTRACT(planduration, planstart);
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 188e26f0e6e..441de55ac24 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -426,7 +426,7 @@ refresh_matview_datafill(DestReceiver *dest, Query *query,
 	CHECK_FOR_INTERRUPTS();
 
 	/* Plan the query which will generate data for the refresh. */
-	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL);
+	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 	/*
 	 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c
index e7c8171c102..ec96c2efcd3 100644
--- a/src/backend/commands/portalcmds.c
+++ b/src/backend/commands/portalcmds.c
@@ -99,7 +99,8 @@ PerformCursorOpen(ParseState *pstate, DeclareCursorStmt *cstmt, ParamListInfo pa
 		elog(ERROR, "non-SELECT statement in DECLARE CURSOR");
 
 	/* Plan the query, applying the specified options */
-	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params);
+	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params,
+						 NULL);
 
 	/*
 	 * Create a portal and copy the plan and query string into its memory.
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 9de39da1757..205d8886a2a 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -291,14 +291,16 @@ static void create_partial_unique_paths(PlannerInfo *root, RelOptInfo *input_rel
  *****************************************************************************/
 PlannedStmt *
 planner(Query *parse, const char *query_string, int cursorOptions,
-		ParamListInfo boundParams)
+		ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 
 	if (planner_hook)
-		result = (*planner_hook) (parse, query_string, cursorOptions, boundParams);
+		result = (*planner_hook) (parse, query_string, cursorOptions,
+								  boundParams, es);
 	else
-		result = standard_planner(parse, query_string, cursorOptions, boundParams);
+		result = standard_planner(parse, query_string, cursorOptions,
+								  boundParams, es);
 
 	pgstat_report_plan_id(result->planId, false);
 
@@ -307,7 +309,7 @@ planner(Query *parse, const char *query_string, int cursorOptions,
 
 PlannedStmt *
 standard_planner(Query *parse, const char *query_string, int cursorOptions,
-				 ParamListInfo boundParams)
+				 ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 	PlannerGlobal *glob;
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index d356830f756..7dd75a490aa 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -37,6 +37,7 @@
 #include "catalog/pg_type.h"
 #include "commands/async.h"
 #include "commands/event_trigger.h"
+#include "commands/explain_state.h"
 #include "commands/prepare.h"
 #include "common/pg_prng.h"
 #include "jit/jit.h"
@@ -884,7 +885,7 @@ pg_rewrite_query(Query *query)
  */
 PlannedStmt *
 pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
-			  ParamListInfo boundParams)
+			  ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *plan;
 
@@ -901,7 +902,7 @@ pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
 		ResetUsage();
 
 	/* call the optimizer */
-	plan = planner(querytree, query_string, cursorOptions, boundParams);
+	plan = planner(querytree, query_string, cursorOptions, boundParams, es);
 
 	if (log_planner_stats)
 		ShowUsage("PLANNER STATISTICS");
@@ -997,7 +998,7 @@ pg_plan_queries(List *querytrees, const char *query_string, int cursorOptions,
 		else
 		{
 			stmt = pg_plan_query(query, query_string, cursorOptions,
-								 boundParams);
+								 boundParams, NULL);
 		}
 
 		stmt_list = lappend(stmt_list, stmt);
diff --git a/src/include/optimizer/optimizer.h b/src/include/optimizer/optimizer.h
index 04878f1f1c2..a8aaefd27e9 100644
--- a/src/include/optimizer/optimizer.h
+++ b/src/include/optimizer/optimizer.h
@@ -24,6 +24,9 @@
 
 #include "nodes/parsenodes.h"
 
+/* avoid including commands/explain_state.h here */
+struct ExplainState;
+
 /*
  * We don't want to include nodes/pathnodes.h here, because non-planner
  * code should generally treat PlannerInfo as an opaque typedef.
@@ -104,7 +107,8 @@ extern PGDLLIMPORT bool enable_distinct_reordering;
 
 extern PlannedStmt *planner(Query *parse, const char *query_string,
 							int cursorOptions,
-							ParamListInfo boundParams);
+							ParamListInfo boundParams,
+							struct ExplainState *es);
 
 extern Expr *expression_planner(Expr *expr);
 extern Expr *expression_planner_with_deps(Expr *expr,
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index f220e9a270d..6c07711913d 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -22,11 +22,15 @@
 #include "nodes/plannodes.h"
 
 
+/* avoid including commands/explain_state.h here */
+struct ExplainState;
+
 /* Hook for plugins to get control in planner() */
 typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   const char *query_string,
 										   int cursorOptions,
-										   ParamListInfo boundParams);
+										   ParamListInfo boundParams,
+										   struct ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
@@ -40,7 +44,8 @@ extern PGDLLIMPORT create_upper_paths_hook_type create_upper_paths_hook;
 
 extern PlannedStmt *standard_planner(Query *parse, const char *query_string,
 									 int cursorOptions,
-									 ParamListInfo boundParams);
+									 ParamListInfo boundParams,
+									 struct ExplainState *es);
 
 extern PlannerInfo *subquery_planner(PlannerGlobal *glob, Query *parse,
 									 PlannerInfo *parent_root,
diff --git a/src/include/tcop/tcopprot.h b/src/include/tcop/tcopprot.h
index a83cc4f4850..90323b10554 100644
--- a/src/include/tcop/tcopprot.h
+++ b/src/include/tcop/tcopprot.h
@@ -20,6 +20,8 @@
 #include "utils/guc.h"
 #include "utils/queryenvironment.h"
 
+/* avoid including commands/explain_state.h here */
+struct ExplainState;
 
 extern PGDLLIMPORT CommandDest whereToSendOutput;
 extern PGDLLIMPORT const char *debug_query_string;
@@ -63,7 +65,8 @@ extern List *pg_analyze_and_rewrite_withcb(RawStmt *parsetree,
 										   QueryEnvironment *queryEnv);
 extern PlannedStmt *pg_plan_query(Query *querytree, const char *query_string,
 								  int cursorOptions,
-								  ParamListInfo boundParams);
+								  ParamListInfo boundParams,
+								  struct ExplainState *es);
 extern List *pg_plan_queries(List *querytrees, const char *query_string,
 							 int cursorOptions,
 							 ParamListInfo boundParams);
diff --git a/src/test/modules/delay_execution/delay_execution.c b/src/test/modules/delay_execution/delay_execution.c
index 7bc97f84a1c..53c4073fce6 100644
--- a/src/test/modules/delay_execution/delay_execution.c
+++ b/src/test/modules/delay_execution/delay_execution.c
@@ -40,17 +40,18 @@ static planner_hook_type prev_planner_hook = NULL;
 /* planner_hook function to provide the desired delay */
 static PlannedStmt *
 delay_execution_planner(Query *parse, const char *query_string,
-						int cursorOptions, ParamListInfo boundParams)
+						int cursorOptions, ParamListInfo boundParams,
+						struct ExplainState *es)
 {
 	PlannedStmt *result;
 
 	/* Invoke the planner, possibly via a previous hook user */
 	if (prev_planner_hook)
 		result = prev_planner_hook(parse, query_string, cursorOptions,
-								   boundParams);
+								   boundParams, es);
 	else
 		result = standard_planner(parse, query_string, cursorOptions,
-								  boundParams);
+								  boundParams, es);
 
 	/* If enabled, delay by taking and releasing the specified lock */
 	if (post_planning_lock_id != 0)
-- 
2.39.5 (Apple Git-154)

From 4228110340d9c5b3d6f0d8a1b51ef8f912a1c412 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 15:22:57 -0400
Subject: [PATCH v5 6/6] not for commit: count distinct joinrels and joinrel
 planning attempts

---
 .../expected/pg_overexplain.out               |  22 ++-
 contrib/pg_overexplain/pg_overexplain.c       | 125 ++++++++++++++++++
 2 files changed, 142 insertions(+), 5 deletions(-)

diff --git a/contrib/pg_overexplain/expected/pg_overexplain.out b/contrib/pg_overexplain/expected/pg_overexplain.out
index 6de02323d7c..d8d3e36d7f1 100644
--- a/contrib/pg_overexplain/expected/pg_overexplain.out
+++ b/contrib/pg_overexplain/expected/pg_overexplain.out
@@ -38,7 +38,9 @@ EXPLAIN (DEBUG) SELECT 1;
    Relation OIDs: none
    Executor Parameter Types: none
    Parse Location: 0 to end
-(11 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(13 rows)
 
 EXPLAIN (RANGE_TABLE) SELECT 1;
                 QUERY PLAN                
@@ -120,6 +122,8 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
  RTI 1 (relation, inherited, in-from-clause):
    Eref: vegetables (id, name, genus)
    Relation: vegetables
@@ -141,7 +145,7 @@ $$);
    Relation Kind: relation
    Relation Lock Mode: AccessShareLock
  Unprunable RTIs: 1 3 4
-(53 rows)
+(55 rows)
 
 -- Test a different output format.
 SELECT explain_filter($$
@@ -241,6 +245,8 @@ $$);
        <Relation-OIDs>NNN...</Relation-OIDs>                        +
        <Executor-Parameter-Types>none</Executor-Parameter-Types>    +
        <Parse-Location>0 to end</Parse-Location>                    +
+       <Total-Joinrel-Attempts>0</Total-Joinrel-Attempts>           +
+       <Distinct-Joinrels>0</Distinct-Joinrels>                     +
      </PlannedStmt>                                                 +
      <Range-Table>                                                  +
        <Range-Table-Entry>                                          +
@@ -345,7 +351,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
-(37 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(39 rows)
 
 SET debug_parallel_query = false;
 RESET enable_seqscan;
@@ -373,7 +381,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 0
    Parse Location: 0 to end
-(15 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(17 rows)
 
 -- Create an index, and then attempt to force a nested loop with inner index
 -- scan so that we can see parameter-related information. Also, let's try
@@ -437,7 +447,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 23
    Parse Location: 0 to end
-(47 rows)
+   Total Joinrel Attempts: 2
+   Distinct Joinrels: 1
+(49 rows)
 
 RESET enable_hashjoin;
 RESET enable_material;
diff --git a/contrib/pg_overexplain/pg_overexplain.c b/contrib/pg_overexplain/pg_overexplain.c
index de824566f8c..e0169fbf7f2 100644
--- a/contrib/pg_overexplain/pg_overexplain.c
+++ b/contrib/pg_overexplain/pg_overexplain.c
@@ -16,6 +16,10 @@
 #include "commands/explain_format.h"
 #include "commands/explain_state.h"
 #include "fmgr.h"
+#include "nodes/makefuncs.h"
+#include "optimizer/extendplan.h"
+#include "optimizer/paths.h"
+#include "optimizer/planner.h"
 #include "parser/parsetree.h"
 #include "storage/lock.h"
 #include "utils/builtins.h"
@@ -32,6 +36,12 @@ typedef struct
 	bool		range_table;
 } overexplain_options;
 
+typedef struct
+{
+	int			total_joinrel_attempts;
+	int			distinct_joinrel_count;
+} overexplain_plannerglobal;
+
 static overexplain_options *overexplain_ensure_options(ExplainState *es);
 static void overexplain_debug_handler(ExplainState *es, DefElem *opt,
 									  ParseState *pstate);
@@ -57,9 +67,28 @@ static void overexplain_bitmapset(const char *qlabel, Bitmapset *bms,
 static void overexplain_intlist(const char *qlabel, List *list,
 								ExplainState *es);
 
+static void overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+										   const char *query_string,
+										   double *tuple_fraction,
+										   struct ExplainState *es);
+static void overexplain_planner_shutdown_hook(PlannerGlobal *glob,
+											  Query *parse,
+											  const char *query_string,
+											  PlannedStmt *pstmt);
+static void overexplain_set_join_pathlist_hook(PlannerInfo *root,
+											   RelOptInfo *joinrel,
+											   RelOptInfo *outerrel,
+											   RelOptInfo *innerrel,
+											   JoinType jointype,
+											   JoinPathExtraData *extra);
+
 static int	es_extension_id;
+static int	planner_extension_id = -1;
 static explain_per_node_hook_type prev_explain_per_node_hook;
 static explain_per_plan_hook_type prev_explain_per_plan_hook;
+static planner_setup_hook_type prev_planner_setup_hook;
+static planner_shutdown_hook_type prev_planner_shutdown_hook;
+static set_join_pathlist_hook_type prev_set_join_pathlist_hook;
 
 /*
  * Initialization we do when this module is loaded.
@@ -70,6 +99,9 @@ _PG_init(void)
 	/* Get an ID that we can use to cache data in an ExplainState. */
 	es_extension_id = GetExplainExtensionId("pg_overexplain");
 
+	/* Get an ID that we can use to cache data in the planner. */
+	planner_extension_id = GetPlannerExtensionId("pg_overexplain");
+
 	/* Register the new EXPLAIN options implemented by this module. */
 	RegisterExtensionExplainOption("debug", overexplain_debug_handler);
 	RegisterExtensionExplainOption("range_table",
@@ -80,6 +112,16 @@ _PG_init(void)
 	explain_per_node_hook = overexplain_per_node_hook;
 	prev_explain_per_plan_hook = explain_per_plan_hook;
 	explain_per_plan_hook = overexplain_per_plan_hook;
+
+	/* Example of planner_setup_hook/planner_shutdown_hook use */
+	prev_planner_setup_hook = planner_setup_hook;
+	planner_setup_hook = overexplain_planner_setup_hook;
+	prev_planner_shutdown_hook = planner_shutdown_hook;
+	planner_shutdown_hook = overexplain_planner_shutdown_hook;
+
+	/* Support for above example */
+	prev_set_join_pathlist_hook = set_join_pathlist_hook;
+	set_join_pathlist_hook = overexplain_set_join_pathlist_hook;
 }
 
 /*
@@ -369,6 +411,29 @@ overexplain_debug(PlannedStmt *plannedstmt, ExplainState *es)
 									 plannedstmt->stmt_len),
 							es);
 
+	{
+		DefElem    *elem = NULL;
+
+		foreach_node(DefElem, de, plannedstmt->extension_state)
+		{
+			if (strcmp(de->defname, "pg_overexplain") == 0)
+			{
+				elem = de;
+				break;
+			}
+		}
+
+		if (elem != NULL)
+		{
+			List	   *l = castNode(List, elem->arg);
+
+			ExplainPropertyInteger("Total Joinrel Attempts", NULL,
+								   intVal(linitial(l)), es);
+			ExplainPropertyInteger("Distinct Joinrels", NULL,
+								   intVal(lsecond(l)), es);
+		}
+	}
+
 	/* Done with this group. */
 	if (es->format == EXPLAIN_FORMAT_TEXT)
 		es->indent--;
@@ -772,3 +837,63 @@ overexplain_intlist(const char *qlabel, List *list, ExplainState *es)
 
 	pfree(buf.data);
 }
+
+static void
+overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+							   const char *query_string,
+							   double *tuple_fraction,
+							   struct ExplainState *es)
+{
+	overexplain_options *options;
+	overexplain_plannerglobal *g;
+
+	if (es != NULL)
+	{
+		options = GetExplainExtensionState(es, es_extension_id);
+		if (options != NULL && options->debug)
+		{
+			g = palloc0_object(overexplain_plannerglobal);
+			SetPlannerGlobalExtensionState(glob, planner_extension_id, g);
+		}
+	}
+}
+
+static void
+overexplain_planner_shutdown_hook(PlannerGlobal *glob, Query *parse,
+								  const char *query_string, PlannedStmt *pstmt)
+{
+	overexplain_plannerglobal *g;
+	DefElem    *elem;
+	List	   *l;
+
+	g = GetPlannerGlobalExtensionState(glob, planner_extension_id);
+	if (g != NULL)
+	{
+		l = list_make2(makeInteger(g->total_joinrel_attempts),
+					   makeInteger(g->distinct_joinrel_count));
+		elem = makeDefElem("pg_overexplain", (Node *) l, -1);
+		pstmt->extension_state = lappend(pstmt->extension_state, elem);
+	}
+}
+
+static void
+overexplain_set_join_pathlist_hook(PlannerInfo *root, RelOptInfo *joinrel,
+								   RelOptInfo *outerrel, RelOptInfo *innerrel,
+								   JoinType jointype, JoinPathExtraData *extra)
+{
+	overexplain_plannerglobal *g;
+
+	g = GetPlannerGlobalExtensionState(root->glob, planner_extension_id);
+
+	if (g != NULL)
+	{
+		g->total_joinrel_attempts++;
+
+		if (GetRelOptInfoExtensionState(joinrel, planner_extension_id) == NULL)
+		{
+			g->distinct_joinrel_count++;
+			/* set any non-NULL value to avoid double-counting */
+			SetRelOptInfoExtensionState(joinrel, planner_extension_id, g);
+		}
+	}
+}
-- 
2.39.5 (Apple Git-154)

From 7b32e6ebacb79508eae5b699fc016294b48ee32a Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 24 Sep 2025 11:21:55 -0400
Subject: [PATCH v6 5/7] Add planner_setup_hook and planner_shutdown_hook.

These hooks allow plugins to get control at the earliest point at
which the PlannerGlobal object is fully initialized, and then just
before it gets destroyed. This is useful in combination with the
extendable plan state facilities (see extendplan.h) and perhaps for
other purposes as well.
---
 src/backend/optimizer/plan/planner.c | 14 ++++++++++++++
 src/include/optimizer/planner.h      | 13 +++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 205d8886a2a..ebcf9ea5851 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -73,6 +73,12 @@ bool		enable_distinct_reordering = true;
 /* Hook for plugins to get control in planner() */
 planner_hook_type planner_hook = NULL;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+planner_setup_hook_type planner_setup_hook = NULL;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+planner_shutdown_hook_type planner_shutdown_hook = NULL;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 create_upper_paths_hook_type create_upper_paths_hook = NULL;
 
@@ -440,6 +446,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 		tuple_fraction = 0.0;
 	}
 
+	/* Allow plugins to take control after we've initialized "glob" */
+	if (planner_setup_hook)
+		(*planner_setup_hook) (glob, parse, query_string, &tuple_fraction, es);
+
 	/* primary planning entry point (may recurse for subqueries) */
 	root = subquery_planner(glob, parse, NULL, false, tuple_fraction, NULL);
 
@@ -618,6 +628,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 			result->jitFlags |= PGJIT_DEFORM;
 	}
 
+	/* Allow plugins to take control before we discard "glob" */
+	if (planner_shutdown_hook)
+		(*planner_shutdown_hook) (glob, parse, query_string, result);
+
 	if (glob->partition_directory != NULL)
 		DestroyPartitionDirectory(glob->partition_directory);
 
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index b31ea2fbbdc..a39389728aa 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -32,6 +32,19 @@ typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+typedef void (*planner_setup_hook_type) (PlannerGlobal *glob, Query *parse,
+										 const char *query_string,
+										 double *tuple_fraction,
+										 ExplainState *es);
+extern PGDLLIMPORT planner_setup_hook_type planner_setup_hook;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+typedef void (*planner_shutdown_hook_type) (PlannerGlobal *glob, Query *parse,
+											const char *query_string,
+											PlannedStmt *pstmt);
+extern PGDLLIMPORT planner_shutdown_hook_type planner_shutdown_hook;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 typedef void (*create_upper_paths_hook_type) (PlannerInfo *root,
 											  UpperRelationKind stage,
-- 
2.39.5 (Apple Git-154)

From 261412985f971bb43ea7fd6c9a076c2e3781ccd4 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 24 Sep 2025 10:48:22 -0400
Subject: [PATCH v6 1/7] Fix array allocation bugs in SetExplainExtensionState.

If we already have an extension_state array but see a new extension_id
much larger than the highest the extension_id we've previously seen,
the old code might have failed to expand the array to a large enough
size, leading to disaster. Also, if we don't have an extension array
at all and need to create one, we should make sure that it's big enough
that we don't have to resize it instantly.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
---
 src/backend/commands/explain_state.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/backend/commands/explain_state.c b/src/backend/commands/explain_state.c
index 60d98d63a62..9fdeeab6436 100644
--- a/src/backend/commands/explain_state.c
+++ b/src/backend/commands/explain_state.c
@@ -281,7 +281,8 @@ SetExplainExtensionState(ExplainState *es, int extension_id, void *opaque)
 	/* If there is no array yet, create one. */
 	if (es->extension_state == NULL)
 	{
-		es->extension_state_allocated = 16;
+		es->extension_state_allocated =
+			Max(16, pg_nextpower2_32(extension_id + 1));
 		es->extension_state =
 			palloc0(es->extension_state_allocated * sizeof(void *));
 	}
@@ -291,7 +292,7 @@ SetExplainExtensionState(ExplainState *es, int extension_id, void *opaque)
 	{
 		int			i;
 
-		i = pg_nextpower2_32(es->extension_state_allocated + 1);
+		i = pg_nextpower2_32(extension_id + 1);
 		es->extension_state = (void **)
 			repalloc0(es->extension_state,
 					  es->extension_state_allocated * sizeof(void *),
-- 
2.39.5 (Apple Git-154)

From 924dc8d7eafbaeb9cc112bea4e87604413d125df Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 24 Sep 2025 11:00:07 -0400
Subject: [PATCH v6 2/7] Allow private state in certain planner data
 structures.

Extension that make extensive use of planner hooks may want to
coordinate their efforts, for example to avoid duplicate computation,
but that's currently difficult because there's no really good way to
pass data between different hooks.

To make that easier, allow for storage of extension-managed private
state in PlannerGlobal, PlannerInfo, and RelOptInfo, along very
similar lines to what we have permitted for ExplainState since commit
c65bc2e1d14a2d4daed7c1921ac518f2c5ac3d17.
---
 src/backend/optimizer/util/Makefile     |   1 +
 src/backend/optimizer/util/extendplan.c | 183 ++++++++++++++++++++++++
 src/backend/optimizer/util/meson.build  |   1 +
 src/include/nodes/pathnodes.h           |  12 ++
 src/include/optimizer/extendplan.h      |  72 ++++++++++
 5 files changed, 269 insertions(+)
 create mode 100644 src/backend/optimizer/util/extendplan.c
 create mode 100644 src/include/optimizer/extendplan.h

diff --git a/src/backend/optimizer/util/Makefile b/src/backend/optimizer/util/Makefile
index 4fb115cb118..87b4c3c0869 100644
--- a/src/backend/optimizer/util/Makefile
+++ b/src/backend/optimizer/util/Makefile
@@ -15,6 +15,7 @@ include $(top_builddir)/src/Makefile.global
 OBJS = \
 	appendinfo.o \
 	clauses.o \
+	extendplan.o \
 	inherit.o \
 	joininfo.o \
 	orclauses.o \
diff --git a/src/backend/optimizer/util/extendplan.c b/src/backend/optimizer/util/extendplan.c
new file mode 100644
index 00000000000..03d32277ba1
--- /dev/null
+++ b/src/backend/optimizer/util/extendplan.c
@@ -0,0 +1,183 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.c
+ *	  Extend core planner objects with additional private state
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994-5, Regents of the University of California
+ *
+ * The interfaces defined in this file make it possible for loadable
+ * modules to store their own private state inside of key planner data
+ * structures -- specifically, the PlannerGlobal, PlannerInfo, and
+ * RelOptInfo structures. This can make it much easier to write
+ * reasonably efficient planner extensions; for instance, code that
+ * uses set_join_pathlist_hook can arrange to compute a key intermediate
+ * result once per joinrel rather than on every call.
+ *
+ * IDENTIFICATION
+ *	  src/backend/optimizer/util/extendplan.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "optimizer/extendplan.h"
+#include "port/pg_bitutils.h"
+#include "utils/memutils.h"
+
+static const char **PlannerExtensionNameArray = NULL;
+static int	PlannerExtensionNamesAssigned = 0;
+static int	PlannerExtensionNamesAllocated = 0;
+
+/*
+ * Map the name of a planner extension to an integer ID.
+ *
+ * Within the lifetime of a particular backend, the same name will be mapped
+ * to the same ID every time. IDs are not stable across backends. Use the ID
+ * that you get from this function to call the remaining functions in this
+ * file.
+ */
+int
+GetPlannerExtensionId(const char *extension_name)
+{
+	/* Search for an existing extension by this name; if found, return ID. */
+	for (int i = 0; i < PlannerExtensionNamesAssigned; ++i)
+		if (strcmp(PlannerExtensionNameArray[i], extension_name) == 0)
+			return i;
+
+	/* If there is no array yet, create one. */
+	if (PlannerExtensionNameArray == NULL)
+	{
+		PlannerExtensionNamesAllocated = 16;
+		PlannerExtensionNameArray = (const char **)
+			MemoryContextAlloc(TopMemoryContext,
+							   PlannerExtensionNamesAllocated
+							   * sizeof(char *));
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (PlannerExtensionNamesAssigned >= PlannerExtensionNamesAllocated)
+	{
+		int			i = pg_nextpower2_32(PlannerExtensionNamesAssigned + 1);
+
+		PlannerExtensionNameArray = (const char **)
+			repalloc(PlannerExtensionNameArray, i * sizeof(char *));
+		PlannerExtensionNamesAllocated = i;
+	}
+
+	/* Assign and return new ID. */
+	PlannerExtensionNameArray[PlannerExtensionNamesAssigned] = extension_name;
+	return PlannerExtensionNamesAssigned++;
+}
+
+/*
+ * Store extension-specific state into a PlannerGlobal.
+ */
+void
+SetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id,
+							   void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (glob->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(glob);
+		glob->extension_state_allocated =
+			Max(4, pg_nextpower2_32(extension_id + 1));
+		sz = glob->extension_state_allocated * sizeof(void *);
+		glob->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= glob->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(extension_id + 1);
+		glob->extension_state = (void **)
+			repalloc0(glob->extension_state,
+					  glob->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		glob->extension_state_allocated = i;
+	}
+
+	glob->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a PlannerInfo.
+ */
+void
+SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+							 void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (root->extension_state == NULL)
+	{
+		Size		sz;
+
+		root->extension_state_allocated =
+			Max(4, pg_nextpower2_32(extension_id + 1));
+		sz = root->extension_state_allocated * sizeof(void *);
+		root->extension_state = MemoryContextAllocZero(root->planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= root->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(extension_id + 1);
+		root->extension_state = (void **)
+			repalloc0(root->extension_state,
+					  root->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		root->extension_state_allocated = i;
+	}
+
+	root->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a RelOptInfo.
+ */
+void
+SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+							void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (rel->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(rel);
+		rel->extension_state_allocated =
+			Max(4, pg_nextpower2_32(extension_id + 1));
+		sz = rel->extension_state_allocated * sizeof(void *);
+		rel->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= rel->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(extension_id + 1);
+		rel->extension_state = (void **)
+			repalloc0(rel->extension_state,
+					  rel->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		rel->extension_state_allocated = i;
+	}
+
+	rel->extension_state[extension_id] = opaque;
+}
diff --git a/src/backend/optimizer/util/meson.build b/src/backend/optimizer/util/meson.build
index b3bf913d096..f71f56e37a1 100644
--- a/src/backend/optimizer/util/meson.build
+++ b/src/backend/optimizer/util/meson.build
@@ -3,6 +3,7 @@
 backend_sources += files(
   'appendinfo.c',
   'clauses.c',
+  'extendplan.c',
   'inherit.c',
   'joininfo.c',
   'orclauses.c',
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index b12a2508d8c..5cf23cba596 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -182,6 +182,10 @@ typedef struct PlannerGlobal
 
 	/* hash table for NOT NULL attnums of relations */
 	struct HTAB *rel_notnullatts_hash pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } PlannerGlobal;
 
 /* macro for fetching the Plan associated with a SubPlan node */
@@ -580,6 +584,10 @@ struct PlannerInfo
 
 	/* PartitionPruneInfos added in this query's plan. */
 	List	   *partPruneInfos;
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 };
 
 
@@ -1091,6 +1099,10 @@ typedef struct RelOptInfo
 	List	  **partexprs pg_node_attr(read_write_ignore);
 	/* Nullable partition key expressions */
 	List	  **nullable_partexprs pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } RelOptInfo;
 
 /*
diff --git a/src/include/optimizer/extendplan.h b/src/include/optimizer/extendplan.h
new file mode 100644
index 00000000000..de9618761dd
--- /dev/null
+++ b/src/include/optimizer/extendplan.h
@@ -0,0 +1,72 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.h
+ *	  Extend core planner objects with additional private state
+ *
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/optimizer/extendplan.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef EXTENDPLAN_H
+#define EXTENDPLAN_H
+
+#include "nodes/pathnodes.h"
+
+extern int	GetPlannerExtensionId(const char *extension_name);
+
+/*
+ * Get extension-specific state from a PlannerGlobal.
+ */
+static inline void *
+GetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= glob->extension_state_allocated)
+		return NULL;
+
+	return glob->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetPlannerInfoExtensionState(PlannerInfo *root, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= root->extension_state_allocated)
+		return NULL;
+
+	return root->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= rel->extension_state_allocated)
+		return NULL;
+
+	return rel->extension_state[extension_id];
+}
+
+/* Functions to store private state into various planner objects */
+extern void SetPlannerGlobalExtensionState(PlannerGlobal *glob,
+										   int extension_id,
+										   void *opaque);
+extern void SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+										 void *opaque);
+extern void SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+										void *opaque);
+
+#endif
-- 
2.39.5 (Apple Git-154)

From de2958ea5a7db4098935cd6754007694a5145ed1 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 20 Aug 2025 15:10:52 -0400
Subject: [PATCH v6 3/7] Remove PlannerInfo's join_search_private method.

Instead, use the new mechanism that allows planner extensions to store
private state inside a PlannerInfo, treating GEQO as an in-core planner
extension.  This is a useful test of the new facility, and also buys
back a few bytes of storage.

To make this work, we must remove innerrel_is_unique_ext's hack of
testing whether join_search_private is set as a proxy for whether
the join search might be retried. Add a flag that extensions can
use to explicitly signal their intentions instead.
---
 src/backend/optimizer/geqo/geqo_eval.c    |  2 +-
 src/backend/optimizer/geqo/geqo_main.c    | 12 ++++++++++--
 src/backend/optimizer/geqo/geqo_random.c  |  7 +++----
 src/backend/optimizer/plan/analyzejoins.c |  9 +++------
 src/backend/optimizer/plan/planner.c      |  1 +
 src/backend/optimizer/prep/prepjointree.c |  1 +
 src/include/nodes/pathnodes.h             |  5 ++---
 src/include/optimizer/geqo.h              | 10 +++++++++-
 8 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/src/backend/optimizer/geqo/geqo_eval.c b/src/backend/optimizer/geqo/geqo_eval.c
index f07d1dc8ac6..7fcb1aa70d1 100644
--- a/src/backend/optimizer/geqo/geqo_eval.c
+++ b/src/backend/optimizer/geqo/geqo_eval.c
@@ -162,7 +162,7 @@ geqo_eval(PlannerInfo *root, Gene *tour, int num_gene)
 RelOptInfo *
 gimme_tree(PlannerInfo *root, Gene *tour, int num_gene)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 	List	   *clumps;
 	int			rel_count;
 
diff --git a/src/backend/optimizer/geqo/geqo_main.c b/src/backend/optimizer/geqo/geqo_main.c
index 38402ce58db..0064556087a 100644
--- a/src/backend/optimizer/geqo/geqo_main.c
+++ b/src/backend/optimizer/geqo/geqo_main.c
@@ -47,6 +47,8 @@ int			Geqo_generations;
 double		Geqo_selection_bias;
 double		Geqo_seed;
 
+/* GEQO is treated as an in-core planner extension */
+int			Geqo_planner_extension_id = -1;
 
 static int	gimme_pool_size(int nr_rel);
 static int	gimme_number_generations(int pool_size);
@@ -98,10 +100,16 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	int			mutations = 0;
 #endif
 
+	if (Geqo_planner_extension_id < 0)
+		Geqo_planner_extension_id = GetPlannerExtensionId("geqo");
+
 /* set up private information */
-	root->join_search_private = &private;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, &private);
 	private.initial_rels = initial_rels;
 
+/* inform core planner that we may replan */
+	root->assumeReplanning = true;
+
 /* initialize private number generator */
 	geqo_set_seed(root, Geqo_seed);
 
@@ -304,7 +312,7 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	free_pool(root, pool);
 
 	/* ... clear root pointer to our private storage */
-	root->join_search_private = NULL;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, NULL);
 
 	return best_rel;
 }
diff --git a/src/backend/optimizer/geqo/geqo_random.c b/src/backend/optimizer/geqo/geqo_random.c
index 6c7a411f69f..46d28baa2e6 100644
--- a/src/backend/optimizer/geqo/geqo_random.c
+++ b/src/backend/optimizer/geqo/geqo_random.c
@@ -15,11 +15,10 @@
 
 #include "optimizer/geqo_random.h"
 
-
 void
 geqo_set_seed(PlannerInfo *root, double seed)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	pg_prng_fseed(&private->random_state, seed);
 }
@@ -27,7 +26,7 @@ geqo_set_seed(PlannerInfo *root, double seed)
 double
 geqo_rand(PlannerInfo *root)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	return pg_prng_double(&private->random_state);
 }
@@ -35,7 +34,7 @@ geqo_rand(PlannerInfo *root)
 int
 geqo_randint(PlannerInfo *root, int upper, int lower)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	/*
 	 * In current usage, "lower" is never negative so we can just use
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 2a3dea88a94..6a3c030e8ef 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -1425,17 +1425,14 @@ innerrel_is_unique_ext(PlannerInfo *root,
 		 *
 		 * However, in normal planning mode, caching this knowledge is totally
 		 * pointless; it won't be queried again, because we build up joinrels
-		 * from smaller to larger.  It is useful in GEQO mode, where the
-		 * knowledge can be carried across successive planning attempts; and
-		 * it's likely to be useful when using join-search plugins, too. Hence
-		 * cache when join_search_private is non-NULL.  (Yeah, that's a hack,
-		 * but it seems reasonable.)
+		 * from smaller to larger.  It's only useful when using GEQO or
+		 * another planner extension that attempts planning multiple times.
 		 *
 		 * Also, allow callers to override that heuristic and force caching;
 		 * that's useful for reduce_unique_semijoins, which calls here before
 		 * the normal join search starts.
 		 */
-		if (force_cache || root->join_search_private)
+		if (force_cache || root->assumeReplanning)
 		{
 			old_context = MemoryContextSwitchTo(root->planner_cxt);
 			innerrel->non_unique_for_rels =
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 41bd8353430..9de39da1757 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -703,6 +703,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse, PlannerInfo *parent_root,
 	root->hasAlternativeSubPlans = false;
 	root->placeholdersFrozen = false;
 	root->hasRecursion = hasRecursion;
+	root->assumeReplanning = false;
 	if (hasRecursion)
 		root->wt_param_id = assign_special_exec_param(root);
 	else
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 35e8d3c183b..4075f7519ca 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -1383,6 +1383,7 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 	subroot->qual_security_level = 0;
 	subroot->placeholdersFrozen = false;
 	subroot->hasRecursion = false;
+	subroot->assumeReplanning = false;
 	subroot->wt_param_id = -1;
 	subroot->non_recursive_path = NULL;
 	/* We don't currently need a top JoinDomain for the subroot */
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 5cf23cba596..bc1e0c1b5cc 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,8 @@ struct PlannerInfo
 	bool		placeholdersFrozen;
 	/* true if planning a recursive WITH item */
 	bool		hasRecursion;
+	/* true if a planner extension may replan this subquery */
+	bool		assumeReplanning;
 
 	/*
 	 * The rangetable index for the RTE_GROUP RTE, or 0 if there is no
@@ -576,9 +578,6 @@ struct PlannerInfo
 	bool	   *isAltSubplan pg_node_attr(read_write_ignore);
 	bool	   *isUsedSubplan pg_node_attr(read_write_ignore);
 
-	/* optional private data for join_search_hook, e.g., GEQO */
-	void	   *join_search_private pg_node_attr(read_write_ignore);
-
 	/* Does this query modify any partition key columns? */
 	bool		partColsUpdated;
 
diff --git a/src/include/optimizer/geqo.h b/src/include/optimizer/geqo.h
index 9f8e0f337aa..3f4872e25e3 100644
--- a/src/include/optimizer/geqo.h
+++ b/src/include/optimizer/geqo.h
@@ -24,6 +24,7 @@
 
 #include "common/pg_prng.h"
 #include "nodes/pathnodes.h"
+#include "optimizer/extendplan.h"
 #include "optimizer/geqo_gene.h"
 
 
@@ -62,6 +63,8 @@ extern PGDLLIMPORT int Geqo_generations;	/* 1 .. inf, or 0 to use default */
 
 extern PGDLLIMPORT double Geqo_selection_bias;
 
+extern PGDLLIMPORT int Geqo_planner_extension_id;
+
 #define DEFAULT_GEQO_SELECTION_BIAS 2.0
 #define MIN_GEQO_SELECTION_BIAS 1.5
 #define MAX_GEQO_SELECTION_BIAS 2.0
@@ -70,7 +73,7 @@ extern PGDLLIMPORT double Geqo_seed;	/* 0 .. 1 */
 
 
 /*
- * Private state for a GEQO run --- accessible via root->join_search_private
+ * Private state for a GEQO run --- accessible via GetGeqoPrivateData
  */
 typedef struct
 {
@@ -78,6 +81,11 @@ typedef struct
 	pg_prng_state random_state; /* PRNG state */
 } GeqoPrivateData;
 
+static inline GeqoPrivateData *
+GetGeqoPrivateData(PlannerInfo *root)
+{
+	return GetPlannerInfoExtensionState(root, Geqo_planner_extension_id);
+}
 
 /* routines in geqo_main.c */
 extern RelOptInfo *geqo(PlannerInfo *root,
-- 
2.39.5 (Apple Git-154)

From e81d1a150b3501b3993a578d559de74f4179ad1f Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 24 Sep 2025 11:18:12 -0400
Subject: [PATCH v6 4/7] Add ExplainState argument to pg_plan_query() and
 planner().

This allows extensions to have access to any data they've stored
in the ExplainState during planning. Unfortunately, it won't help
with EXPLAIN EXECUTE is used, but since that case is less common,
this still seems like an improvement.
---
 contrib/pg_stat_statements/pg_stat_statements.c    | 14 ++++++++------
 src/backend/commands/copyto.c                      |  2 +-
 src/backend/commands/createas.c                    |  2 +-
 src/backend/commands/explain.c                     |  2 +-
 src/backend/commands/matview.c                     |  2 +-
 src/backend/commands/portalcmds.c                  |  3 ++-
 src/backend/optimizer/plan/planner.c               | 10 ++++++----
 src/backend/tcop/postgres.c                        |  7 ++++---
 src/include/optimizer/optimizer.h                  |  5 ++++-
 src/include/optimizer/planner.h                    |  8 ++++++--
 src/include/tcop/tcopprot.h                        |  4 +++-
 src/test/modules/delay_execution/delay_execution.c |  7 ++++---
 12 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 0bb0f933399..d6af2f8efbf 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -337,7 +337,8 @@ static void pgss_post_parse_analyze(ParseState *pstate, Query *query,
 static PlannedStmt *pgss_planner(Query *parse,
 								 const char *query_string,
 								 int cursorOptions,
-								 ParamListInfo boundParams);
+								 ParamListInfo boundParams,
+								 ExplainState *es);
 static void pgss_ExecutorStart(QueryDesc *queryDesc, int eflags);
 static void pgss_ExecutorRun(QueryDesc *queryDesc,
 							 ScanDirection direction,
@@ -893,7 +894,8 @@ static PlannedStmt *
 pgss_planner(Query *parse,
 			 const char *query_string,
 			 int cursorOptions,
-			 ParamListInfo boundParams)
+			 ParamListInfo boundParams,
+			 ExplainState *es)
 {
 	PlannedStmt *result;
 
@@ -928,10 +930,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
@@ -977,10 +979,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
diff --git a/src/backend/commands/copyto.c b/src/backend/commands/copyto.c
index 67b94b91cae..e5781155cdf 100644
--- a/src/backend/commands/copyto.c
+++ b/src/backend/commands/copyto.c
@@ -796,7 +796,7 @@ BeginCopyTo(ParseState *pstate,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, NULL);
+							 CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 		/*
 		 * With row-level security and a user using "COPY relation TO", we
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1ccc2e55c64 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -321,7 +321,7 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, params);
+							 CURSOR_OPT_PARALLEL_OK, params, NULL);
 
 		/*
 		 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 207f86f1d39..82d14db8d68 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -351,7 +351,7 @@ standard_ExplainOneQuery(Query *query, int cursorOptions,
 	INSTR_TIME_SET_CURRENT(planstart);
 
 	/* plan the query */
-	plan = pg_plan_query(query, queryString, cursorOptions, params);
+	plan = pg_plan_query(query, queryString, cursorOptions, params, es);
 
 	INSTR_TIME_SET_CURRENT(planduration);
 	INSTR_TIME_SUBTRACT(planduration, planstart);
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 188e26f0e6e..441de55ac24 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -426,7 +426,7 @@ refresh_matview_datafill(DestReceiver *dest, Query *query,
 	CHECK_FOR_INTERRUPTS();
 
 	/* Plan the query which will generate data for the refresh. */
-	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL);
+	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 	/*
 	 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c
index e7c8171c102..ec96c2efcd3 100644
--- a/src/backend/commands/portalcmds.c
+++ b/src/backend/commands/portalcmds.c
@@ -99,7 +99,8 @@ PerformCursorOpen(ParseState *pstate, DeclareCursorStmt *cstmt, ParamListInfo pa
 		elog(ERROR, "non-SELECT statement in DECLARE CURSOR");
 
 	/* Plan the query, applying the specified options */
-	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params);
+	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params,
+						 NULL);
 
 	/*
 	 * Create a portal and copy the plan and query string into its memory.
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 9de39da1757..205d8886a2a 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -291,14 +291,16 @@ static void create_partial_unique_paths(PlannerInfo *root, RelOptInfo *input_rel
  *****************************************************************************/
 PlannedStmt *
 planner(Query *parse, const char *query_string, int cursorOptions,
-		ParamListInfo boundParams)
+		ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 
 	if (planner_hook)
-		result = (*planner_hook) (parse, query_string, cursorOptions, boundParams);
+		result = (*planner_hook) (parse, query_string, cursorOptions,
+								  boundParams, es);
 	else
-		result = standard_planner(parse, query_string, cursorOptions, boundParams);
+		result = standard_planner(parse, query_string, cursorOptions,
+								  boundParams, es);
 
 	pgstat_report_plan_id(result->planId, false);
 
@@ -307,7 +309,7 @@ planner(Query *parse, const char *query_string, int cursorOptions,
 
 PlannedStmt *
 standard_planner(Query *parse, const char *query_string, int cursorOptions,
-				 ParamListInfo boundParams)
+				 ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 	PlannerGlobal *glob;
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index d356830f756..7dd75a490aa 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -37,6 +37,7 @@
 #include "catalog/pg_type.h"
 #include "commands/async.h"
 #include "commands/event_trigger.h"
+#include "commands/explain_state.h"
 #include "commands/prepare.h"
 #include "common/pg_prng.h"
 #include "jit/jit.h"
@@ -884,7 +885,7 @@ pg_rewrite_query(Query *query)
  */
 PlannedStmt *
 pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
-			  ParamListInfo boundParams)
+			  ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *plan;
 
@@ -901,7 +902,7 @@ pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
 		ResetUsage();
 
 	/* call the optimizer */
-	plan = planner(querytree, query_string, cursorOptions, boundParams);
+	plan = planner(querytree, query_string, cursorOptions, boundParams, es);
 
 	if (log_planner_stats)
 		ShowUsage("PLANNER STATISTICS");
@@ -997,7 +998,7 @@ pg_plan_queries(List *querytrees, const char *query_string, int cursorOptions,
 		else
 		{
 			stmt = pg_plan_query(query, query_string, cursorOptions,
-								 boundParams);
+								 boundParams, NULL);
 		}
 
 		stmt_list = lappend(stmt_list, stmt);
diff --git a/src/include/optimizer/optimizer.h b/src/include/optimizer/optimizer.h
index 04878f1f1c2..a34113903c0 100644
--- a/src/include/optimizer/optimizer.h
+++ b/src/include/optimizer/optimizer.h
@@ -24,6 +24,8 @@
 
 #include "nodes/parsenodes.h"
 
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
+
 /*
  * We don't want to include nodes/pathnodes.h here, because non-planner
  * code should generally treat PlannerInfo as an opaque typedef.
@@ -104,7 +106,8 @@ extern PGDLLIMPORT bool enable_distinct_reordering;
 
 extern PlannedStmt *planner(Query *parse, const char *query_string,
 							int cursorOptions,
-							ParamListInfo boundParams);
+							ParamListInfo boundParams,
+							ExplainState *es);
 
 extern Expr *expression_planner(Expr *expr);
 extern Expr *expression_planner_with_deps(Expr *expr,
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index f220e9a270d..b31ea2fbbdc 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -22,11 +22,14 @@
 #include "nodes/plannodes.h"
 
 
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
+
 /* Hook for plugins to get control in planner() */
 typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   const char *query_string,
 										   int cursorOptions,
-										   ParamListInfo boundParams);
+										   ParamListInfo boundParams,
+										   ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
@@ -40,7 +43,8 @@ extern PGDLLIMPORT create_upper_paths_hook_type create_upper_paths_hook;
 
 extern PlannedStmt *standard_planner(Query *parse, const char *query_string,
 									 int cursorOptions,
-									 ParamListInfo boundParams);
+									 ParamListInfo boundParams,
+									 ExplainState *es);
 
 extern PlannerInfo *subquery_planner(PlannerGlobal *glob, Query *parse,
 									 PlannerInfo *parent_root,
diff --git a/src/include/tcop/tcopprot.h b/src/include/tcop/tcopprot.h
index a83cc4f4850..c1bcfdec673 100644
--- a/src/include/tcop/tcopprot.h
+++ b/src/include/tcop/tcopprot.h
@@ -20,6 +20,7 @@
 #include "utils/guc.h"
 #include "utils/queryenvironment.h"
 
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
 
 extern PGDLLIMPORT CommandDest whereToSendOutput;
 extern PGDLLIMPORT const char *debug_query_string;
@@ -63,7 +64,8 @@ extern List *pg_analyze_and_rewrite_withcb(RawStmt *parsetree,
 										   QueryEnvironment *queryEnv);
 extern PlannedStmt *pg_plan_query(Query *querytree, const char *query_string,
 								  int cursorOptions,
-								  ParamListInfo boundParams);
+								  ParamListInfo boundParams,
+								  ExplainState *es);
 extern List *pg_plan_queries(List *querytrees, const char *query_string,
 							 int cursorOptions,
 							 ParamListInfo boundParams);
diff --git a/src/test/modules/delay_execution/delay_execution.c b/src/test/modules/delay_execution/delay_execution.c
index 7bc97f84a1c..d933e9a6e53 100644
--- a/src/test/modules/delay_execution/delay_execution.c
+++ b/src/test/modules/delay_execution/delay_execution.c
@@ -40,17 +40,18 @@ static planner_hook_type prev_planner_hook = NULL;
 /* planner_hook function to provide the desired delay */
 static PlannedStmt *
 delay_execution_planner(Query *parse, const char *query_string,
-						int cursorOptions, ParamListInfo boundParams)
+						int cursorOptions, ParamListInfo boundParams,
+						ExplainState *es)
 {
 	PlannedStmt *result;
 
 	/* Invoke the planner, possibly via a previous hook user */
 	if (prev_planner_hook)
 		result = prev_planner_hook(parse, query_string, cursorOptions,
-								   boundParams);
+								   boundParams, es);
 	else
 		result = standard_planner(parse, query_string, cursorOptions,
-								  boundParams);
+								  boundParams, es);
 
 	/* If enabled, delay by taking and releasing the specified lock */
 	if (post_planning_lock_id != 0)
-- 
2.39.5 (Apple Git-154)

From 96921b906a3d0c811b433ce1b9c00f1c58f6c29a Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 14:29:02 -0400
Subject: [PATCH v6 6/7] Add extension_state member to PlannedStmt.

Extensions can stash data computed at plan time into this list using
planner_shutdown_hook (or perhaps other mechanisms) and then access
it from any code that has access to the PlannedStmt (such as explain
hooks), allowing for extensible debugging and instrumentation of
plans.
---
 src/include/nodes/plannodes.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 3d196f5078e..77ec2bc10b2 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -149,6 +149,15 @@ typedef struct PlannedStmt
 	/* non-null if this is utility stmt */
 	Node	   *utilityStmt;
 
+	/*
+	 * DefElem objects added by extensions, e.g. using planner_shutdown_hook
+	 *
+	 * Set each DefElem's defname to the name of the plugin or extension, and
+	 * the argument to a tree of nodes that all have copy and read/write
+	 * support.
+	 */
+	List	   *extension_state;
+
 	/* statement location in source string (copied from Query) */
 	/* start location, or -1 if unknown */
 	ParseLoc	stmt_location;
-- 
2.39.5 (Apple Git-154)

From 19613e063b93bd67cf452cc6d72afb853301fb65 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 15:22:57 -0400
Subject: [PATCH v6 7/7] not for commit: count distinct joinrels and joinrel
 planning attempts

---
 .../expected/pg_overexplain.out               |  22 ++-
 contrib/pg_overexplain/pg_overexplain.c       | 125 ++++++++++++++++++
 2 files changed, 142 insertions(+), 5 deletions(-)

diff --git a/contrib/pg_overexplain/expected/pg_overexplain.out b/contrib/pg_overexplain/expected/pg_overexplain.out
index 55d34666d87..48251298f05 100644
--- a/contrib/pg_overexplain/expected/pg_overexplain.out
+++ b/contrib/pg_overexplain/expected/pg_overexplain.out
@@ -38,7 +38,9 @@ EXPLAIN (DEBUG) SELECT 1;
    Relation OIDs: none
    Executor Parameter Types: none
    Parse Location: 0 to end
-(11 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(13 rows)
 
 EXPLAIN (RANGE_TABLE) SELECT 1;
                 QUERY PLAN                
@@ -121,6 +123,8 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
  RTI 1 (relation, inherited, in-from-clause):
    Eref: vegetables (id, name, genus)
    Relation: vegetables
@@ -142,7 +146,7 @@ $$);
    Relation Kind: relation
    Relation Lock Mode: AccessShareLock
  Unprunable RTIs: 1 3 4
-(53 rows)
+(55 rows)
 
 -- Test a different output format.
 SELECT explain_filter($$
@@ -242,6 +246,8 @@ $$);
        <Relation-OIDs>NNN...</Relation-OIDs>                        +
        <Executor-Parameter-Types>none</Executor-Parameter-Types>    +
        <Parse-Location>0 to end</Parse-Location>                    +
+       <Total-Joinrel-Attempts>0</Total-Joinrel-Attempts>           +
+       <Distinct-Joinrels>0</Distinct-Joinrels>                     +
      </PlannedStmt>                                                 +
      <Range-Table>                                                  +
        <Range-Table-Entry>                                          +
@@ -346,7 +352,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
-(37 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(39 rows)
 
 SET debug_parallel_query = false;
 RESET enable_seqscan;
@@ -374,7 +382,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 0
    Parse Location: 0 to end
-(15 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(17 rows)
 
 -- Create an index, and then attempt to force a nested loop with inner index
 -- scan so that we can see parameter-related information. Also, let's try
@@ -438,7 +448,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 23
    Parse Location: 0 to end
-(47 rows)
+   Total Joinrel Attempts: 2
+   Distinct Joinrels: 1
+(49 rows)
 
 RESET enable_hashjoin;
 RESET enable_material;
diff --git a/contrib/pg_overexplain/pg_overexplain.c b/contrib/pg_overexplain/pg_overexplain.c
index bd70b6d9d5e..93d2051f4fb 100644
--- a/contrib/pg_overexplain/pg_overexplain.c
+++ b/contrib/pg_overexplain/pg_overexplain.c
@@ -16,6 +16,10 @@
 #include "commands/explain_format.h"
 #include "commands/explain_state.h"
 #include "fmgr.h"
+#include "nodes/makefuncs.h"
+#include "optimizer/extendplan.h"
+#include "optimizer/paths.h"
+#include "optimizer/planner.h"
 #include "parser/parsetree.h"
 #include "storage/lock.h"
 #include "utils/builtins.h"
@@ -32,6 +36,12 @@ typedef struct
 	bool		range_table;
 } overexplain_options;
 
+typedef struct
+{
+	int			total_joinrel_attempts;
+	int			distinct_joinrel_count;
+} overexplain_plannerglobal;
+
 static overexplain_options *overexplain_ensure_options(ExplainState *es);
 static void overexplain_debug_handler(ExplainState *es, DefElem *opt,
 									  ParseState *pstate);
@@ -57,9 +67,28 @@ static void overexplain_bitmapset(const char *qlabel, Bitmapset *bms,
 static void overexplain_intlist(const char *qlabel, List *list,
 								ExplainState *es);
 
+static void overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+										   const char *query_string,
+										   double *tuple_fraction,
+										   struct ExplainState *es);
+static void overexplain_planner_shutdown_hook(PlannerGlobal *glob,
+											  Query *parse,
+											  const char *query_string,
+											  PlannedStmt *pstmt);
+static void overexplain_set_join_pathlist_hook(PlannerInfo *root,
+											   RelOptInfo *joinrel,
+											   RelOptInfo *outerrel,
+											   RelOptInfo *innerrel,
+											   JoinType jointype,
+											   JoinPathExtraData *extra);
+
 static int	es_extension_id;
+static int	planner_extension_id = -1;
 static explain_per_node_hook_type prev_explain_per_node_hook;
 static explain_per_plan_hook_type prev_explain_per_plan_hook;
+static planner_setup_hook_type prev_planner_setup_hook;
+static planner_shutdown_hook_type prev_planner_shutdown_hook;
+static set_join_pathlist_hook_type prev_set_join_pathlist_hook;
 
 /*
  * Initialization we do when this module is loaded.
@@ -70,6 +99,9 @@ _PG_init(void)
 	/* Get an ID that we can use to cache data in an ExplainState. */
 	es_extension_id = GetExplainExtensionId("pg_overexplain");
 
+	/* Get an ID that we can use to cache data in the planner. */
+	planner_extension_id = GetPlannerExtensionId("pg_overexplain");
+
 	/* Register the new EXPLAIN options implemented by this module. */
 	RegisterExtensionExplainOption("debug", overexplain_debug_handler);
 	RegisterExtensionExplainOption("range_table",
@@ -80,6 +112,16 @@ _PG_init(void)
 	explain_per_node_hook = overexplain_per_node_hook;
 	prev_explain_per_plan_hook = explain_per_plan_hook;
 	explain_per_plan_hook = overexplain_per_plan_hook;
+
+	/* Example of planner_setup_hook/planner_shutdown_hook use */
+	prev_planner_setup_hook = planner_setup_hook;
+	planner_setup_hook = overexplain_planner_setup_hook;
+	prev_planner_shutdown_hook = planner_shutdown_hook;
+	planner_shutdown_hook = overexplain_planner_shutdown_hook;
+
+	/* Support for above example */
+	prev_set_join_pathlist_hook = set_join_pathlist_hook;
+	set_join_pathlist_hook = overexplain_set_join_pathlist_hook;
 }
 
 /*
@@ -381,6 +423,29 @@ overexplain_debug(PlannedStmt *plannedstmt, ExplainState *es)
 									 plannedstmt->stmt_len),
 							es);
 
+	{
+		DefElem    *elem = NULL;
+
+		foreach_node(DefElem, de, plannedstmt->extension_state)
+		{
+			if (strcmp(de->defname, "pg_overexplain") == 0)
+			{
+				elem = de;
+				break;
+			}
+		}
+
+		if (elem != NULL)
+		{
+			List	   *l = castNode(List, elem->arg);
+
+			ExplainPropertyInteger("Total Joinrel Attempts", NULL,
+								   intVal(linitial(l)), es);
+			ExplainPropertyInteger("Distinct Joinrels", NULL,
+								   intVal(lsecond(l)), es);
+		}
+	}
+
 	/* Done with this group. */
 	if (es->format == EXPLAIN_FORMAT_TEXT)
 		es->indent--;
@@ -784,3 +849,63 @@ overexplain_intlist(const char *qlabel, List *list, ExplainState *es)
 
 	pfree(buf.data);
 }
+
+static void
+overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+							   const char *query_string,
+							   double *tuple_fraction,
+							   struct ExplainState *es)
+{
+	overexplain_options *options;
+	overexplain_plannerglobal *g;
+
+	if (es != NULL)
+	{
+		options = GetExplainExtensionState(es, es_extension_id);
+		if (options != NULL && options->debug)
+		{
+			g = palloc0_object(overexplain_plannerglobal);
+			SetPlannerGlobalExtensionState(glob, planner_extension_id, g);
+		}
+	}
+}
+
+static void
+overexplain_planner_shutdown_hook(PlannerGlobal *glob, Query *parse,
+								  const char *query_string, PlannedStmt *pstmt)
+{
+	overexplain_plannerglobal *g;
+	DefElem    *elem;
+	List	   *l;
+
+	g = GetPlannerGlobalExtensionState(glob, planner_extension_id);
+	if (g != NULL)
+	{
+		l = list_make2(makeInteger(g->total_joinrel_attempts),
+					   makeInteger(g->distinct_joinrel_count));
+		elem = makeDefElem("pg_overexplain", (Node *) l, -1);
+		pstmt->extension_state = lappend(pstmt->extension_state, elem);
+	}
+}
+
+static void
+overexplain_set_join_pathlist_hook(PlannerInfo *root, RelOptInfo *joinrel,
+								   RelOptInfo *outerrel, RelOptInfo *innerrel,
+								   JoinType jointype, JoinPathExtraData *extra)
+{
+	overexplain_plannerglobal *g;
+
+	g = GetPlannerGlobalExtensionState(root->glob, planner_extension_id);
+
+	if (g != NULL)
+	{
+		g->total_joinrel_attempts++;
+
+		if (GetRelOptInfoExtensionState(joinrel, planner_extension_id) == NULL)
+		{
+			g->distinct_joinrel_count++;
+			/* set any non-NULL value to avoid double-counting */
+			SetRelOptInfoExtensionState(joinrel, planner_extension_id, g);
+		}
+	}
+}
-- 
2.39.5 (Apple Git-154)

From efdf3e1dafa0b509a9a14692c100ade688f91398 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 24 Sep 2025 11:21:55 -0400
Subject: [PATCH v7 4/6] Add planner_setup_hook and planner_shutdown_hook.

These hooks allow plugins to get control at the earliest point at
which the PlannerGlobal object is fully initialized, and then just
before it gets destroyed. This is useful in combination with the
extendable plan state facilities (see extendplan.h) and perhaps for
other purposes as well.
---
 src/backend/optimizer/plan/planner.c | 14 ++++++++++++++
 src/include/optimizer/planner.h      | 13 +++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 205d8886a2a..ebcf9ea5851 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -73,6 +73,12 @@ bool		enable_distinct_reordering = true;
 /* Hook for plugins to get control in planner() */
 planner_hook_type planner_hook = NULL;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+planner_setup_hook_type planner_setup_hook = NULL;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+planner_shutdown_hook_type planner_shutdown_hook = NULL;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 create_upper_paths_hook_type create_upper_paths_hook = NULL;
 
@@ -440,6 +446,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 		tuple_fraction = 0.0;
 	}
 
+	/* Allow plugins to take control after we've initialized "glob" */
+	if (planner_setup_hook)
+		(*planner_setup_hook) (glob, parse, query_string, &tuple_fraction, es);
+
 	/* primary planning entry point (may recurse for subqueries) */
 	root = subquery_planner(glob, parse, NULL, false, tuple_fraction, NULL);
 
@@ -618,6 +628,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 			result->jitFlags |= PGJIT_DEFORM;
 	}
 
+	/* Allow plugins to take control before we discard "glob" */
+	if (planner_shutdown_hook)
+		(*planner_shutdown_hook) (glob, parse, query_string, result);
+
 	if (glob->partition_directory != NULL)
 		DestroyPartitionDirectory(glob->partition_directory);
 
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index b31ea2fbbdc..a39389728aa 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -32,6 +32,19 @@ typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+typedef void (*planner_setup_hook_type) (PlannerGlobal *glob, Query *parse,
+										 const char *query_string,
+										 double *tuple_fraction,
+										 ExplainState *es);
+extern PGDLLIMPORT planner_setup_hook_type planner_setup_hook;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+typedef void (*planner_shutdown_hook_type) (PlannerGlobal *glob, Query *parse,
+											const char *query_string,
+											PlannedStmt *pstmt);
+extern PGDLLIMPORT planner_shutdown_hook_type planner_shutdown_hook;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 typedef void (*create_upper_paths_hook_type) (PlannerInfo *root,
 											  UpperRelationKind stage,
-- 
2.39.5 (Apple Git-154)

From 086b9395a959ad9bc640286a1e24da06fc915b7c Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 24 Sep 2025 11:00:07 -0400
Subject: [PATCH v7 1/6] Allow private state in certain planner data
 structures.

Extension that make extensive use of planner hooks may want to
coordinate their efforts, for example to avoid duplicate computation,
but that's currently difficult because there's no really good way to
pass data between different hooks.

To make that easier, allow for storage of extension-managed private
state in PlannerGlobal, PlannerInfo, and RelOptInfo, along very
similar lines to what we have permitted for ExplainState since commit
c65bc2e1d14a2d4daed7c1921ac518f2c5ac3d17.
---
 src/backend/optimizer/util/Makefile     |   1 +
 src/backend/optimizer/util/extendplan.c | 183 ++++++++++++++++++++++++
 src/backend/optimizer/util/meson.build  |   1 +
 src/include/nodes/pathnodes.h           |  12 ++
 src/include/optimizer/extendplan.h      |  72 ++++++++++
 5 files changed, 269 insertions(+)
 create mode 100644 src/backend/optimizer/util/extendplan.c
 create mode 100644 src/include/optimizer/extendplan.h

diff --git a/src/backend/optimizer/util/Makefile b/src/backend/optimizer/util/Makefile
index 4fb115cb118..87b4c3c0869 100644
--- a/src/backend/optimizer/util/Makefile
+++ b/src/backend/optimizer/util/Makefile
@@ -15,6 +15,7 @@ include $(top_builddir)/src/Makefile.global
 OBJS = \
 	appendinfo.o \
 	clauses.o \
+	extendplan.o \
 	inherit.o \
 	joininfo.o \
 	orclauses.o \
diff --git a/src/backend/optimizer/util/extendplan.c b/src/backend/optimizer/util/extendplan.c
new file mode 100644
index 00000000000..03d32277ba1
--- /dev/null
+++ b/src/backend/optimizer/util/extendplan.c
@@ -0,0 +1,183 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.c
+ *	  Extend core planner objects with additional private state
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994-5, Regents of the University of California
+ *
+ * The interfaces defined in this file make it possible for loadable
+ * modules to store their own private state inside of key planner data
+ * structures -- specifically, the PlannerGlobal, PlannerInfo, and
+ * RelOptInfo structures. This can make it much easier to write
+ * reasonably efficient planner extensions; for instance, code that
+ * uses set_join_pathlist_hook can arrange to compute a key intermediate
+ * result once per joinrel rather than on every call.
+ *
+ * IDENTIFICATION
+ *	  src/backend/optimizer/util/extendplan.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "optimizer/extendplan.h"
+#include "port/pg_bitutils.h"
+#include "utils/memutils.h"
+
+static const char **PlannerExtensionNameArray = NULL;
+static int	PlannerExtensionNamesAssigned = 0;
+static int	PlannerExtensionNamesAllocated = 0;
+
+/*
+ * Map the name of a planner extension to an integer ID.
+ *
+ * Within the lifetime of a particular backend, the same name will be mapped
+ * to the same ID every time. IDs are not stable across backends. Use the ID
+ * that you get from this function to call the remaining functions in this
+ * file.
+ */
+int
+GetPlannerExtensionId(const char *extension_name)
+{
+	/* Search for an existing extension by this name; if found, return ID. */
+	for (int i = 0; i < PlannerExtensionNamesAssigned; ++i)
+		if (strcmp(PlannerExtensionNameArray[i], extension_name) == 0)
+			return i;
+
+	/* If there is no array yet, create one. */
+	if (PlannerExtensionNameArray == NULL)
+	{
+		PlannerExtensionNamesAllocated = 16;
+		PlannerExtensionNameArray = (const char **)
+			MemoryContextAlloc(TopMemoryContext,
+							   PlannerExtensionNamesAllocated
+							   * sizeof(char *));
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (PlannerExtensionNamesAssigned >= PlannerExtensionNamesAllocated)
+	{
+		int			i = pg_nextpower2_32(PlannerExtensionNamesAssigned + 1);
+
+		PlannerExtensionNameArray = (const char **)
+			repalloc(PlannerExtensionNameArray, i * sizeof(char *));
+		PlannerExtensionNamesAllocated = i;
+	}
+
+	/* Assign and return new ID. */
+	PlannerExtensionNameArray[PlannerExtensionNamesAssigned] = extension_name;
+	return PlannerExtensionNamesAssigned++;
+}
+
+/*
+ * Store extension-specific state into a PlannerGlobal.
+ */
+void
+SetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id,
+							   void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (glob->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(glob);
+		glob->extension_state_allocated =
+			Max(4, pg_nextpower2_32(extension_id + 1));
+		sz = glob->extension_state_allocated * sizeof(void *);
+		glob->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= glob->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(extension_id + 1);
+		glob->extension_state = (void **)
+			repalloc0(glob->extension_state,
+					  glob->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		glob->extension_state_allocated = i;
+	}
+
+	glob->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a PlannerInfo.
+ */
+void
+SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+							 void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (root->extension_state == NULL)
+	{
+		Size		sz;
+
+		root->extension_state_allocated =
+			Max(4, pg_nextpower2_32(extension_id + 1));
+		sz = root->extension_state_allocated * sizeof(void *);
+		root->extension_state = MemoryContextAllocZero(root->planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= root->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(extension_id + 1);
+		root->extension_state = (void **)
+			repalloc0(root->extension_state,
+					  root->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		root->extension_state_allocated = i;
+	}
+
+	root->extension_state[extension_id] = opaque;
+}
+
+/*
+ * Store extension-specific state into a RelOptInfo.
+ */
+void
+SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+							void *opaque)
+{
+	Assert(extension_id >= 0);
+
+	/* If there is no array yet, create one. */
+	if (rel->extension_state == NULL)
+	{
+		MemoryContext planner_cxt;
+		Size		sz;
+
+		planner_cxt = GetMemoryChunkContext(rel);
+		rel->extension_state_allocated =
+			Max(4, pg_nextpower2_32(extension_id + 1));
+		sz = rel->extension_state_allocated * sizeof(void *);
+		rel->extension_state = MemoryContextAllocZero(planner_cxt, sz);
+	}
+
+	/* If there's an array but it's currently full, expand it. */
+	if (extension_id >= rel->extension_state_allocated)
+	{
+		int			i;
+
+		i = pg_nextpower2_32(extension_id + 1);
+		rel->extension_state = (void **)
+			repalloc0(rel->extension_state,
+					  rel->extension_state_allocated * sizeof(void *),
+					  i * sizeof(void *));
+		rel->extension_state_allocated = i;
+	}
+
+	rel->extension_state[extension_id] = opaque;
+}
diff --git a/src/backend/optimizer/util/meson.build b/src/backend/optimizer/util/meson.build
index b3bf913d096..f71f56e37a1 100644
--- a/src/backend/optimizer/util/meson.build
+++ b/src/backend/optimizer/util/meson.build
@@ -3,6 +3,7 @@
 backend_sources += files(
   'appendinfo.c',
   'clauses.c',
+  'extendplan.c',
   'inherit.c',
   'joininfo.c',
   'orclauses.c',
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index b12a2508d8c..5cf23cba596 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -182,6 +182,10 @@ typedef struct PlannerGlobal
 
 	/* hash table for NOT NULL attnums of relations */
 	struct HTAB *rel_notnullatts_hash pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } PlannerGlobal;
 
 /* macro for fetching the Plan associated with a SubPlan node */
@@ -580,6 +584,10 @@ struct PlannerInfo
 
 	/* PartitionPruneInfos added in this query's plan. */
 	List	   *partPruneInfos;
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 };
 
 
@@ -1091,6 +1099,10 @@ typedef struct RelOptInfo
 	List	  **partexprs pg_node_attr(read_write_ignore);
 	/* Nullable partition key expressions */
 	List	  **nullable_partexprs pg_node_attr(read_write_ignore);
+
+	/* extension state */
+	void	  **extension_state pg_node_attr(read_write_ignore);
+	int			extension_state_allocated;
 } RelOptInfo;
 
 /*
diff --git a/src/include/optimizer/extendplan.h b/src/include/optimizer/extendplan.h
new file mode 100644
index 00000000000..de9618761dd
--- /dev/null
+++ b/src/include/optimizer/extendplan.h
@@ -0,0 +1,72 @@
+/*-------------------------------------------------------------------------
+ *
+ * extendplan.h
+ *	  Extend core planner objects with additional private state
+ *
+ *
+ * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/optimizer/extendplan.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef EXTENDPLAN_H
+#define EXTENDPLAN_H
+
+#include "nodes/pathnodes.h"
+
+extern int	GetPlannerExtensionId(const char *extension_name);
+
+/*
+ * Get extension-specific state from a PlannerGlobal.
+ */
+static inline void *
+GetPlannerGlobalExtensionState(PlannerGlobal *glob, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= glob->extension_state_allocated)
+		return NULL;
+
+	return glob->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetPlannerInfoExtensionState(PlannerInfo *root, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= root->extension_state_allocated)
+		return NULL;
+
+	return root->extension_state[extension_id];
+}
+
+/*
+ * Get extension-specific state from a PlannerInfo.
+ */
+static inline void *
+GetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id)
+{
+	Assert(extension_id >= 0);
+
+	if (extension_id >= rel->extension_state_allocated)
+		return NULL;
+
+	return rel->extension_state[extension_id];
+}
+
+/* Functions to store private state into various planner objects */
+extern void SetPlannerGlobalExtensionState(PlannerGlobal *glob,
+										   int extension_id,
+										   void *opaque);
+extern void SetPlannerInfoExtensionState(PlannerInfo *root, int extension_id,
+										 void *opaque);
+extern void SetRelOptInfoExtensionState(RelOptInfo *rel, int extension_id,
+										void *opaque);
+
+#endif
-- 
2.39.5 (Apple Git-154)

From 924d15c2058c4300b5eaccc5e5a7608b47f643c0 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 20 Aug 2025 15:10:52 -0400
Subject: [PATCH v7 2/6] Remove PlannerInfo's join_search_private method.

Instead, use the new mechanism that allows planner extensions to store
private state inside a PlannerInfo, treating GEQO as an in-core planner
extension.  This is a useful test of the new facility, and also buys
back a few bytes of storage.

To make this work, we must remove innerrel_is_unique_ext's hack of
testing whether join_search_private is set as a proxy for whether
the join search might be retried. Add a flag that extensions can
use to explicitly signal their intentions instead.
---
 src/backend/optimizer/geqo/geqo_eval.c    |  2 +-
 src/backend/optimizer/geqo/geqo_main.c    | 12 ++++++++++--
 src/backend/optimizer/geqo/geqo_random.c  |  7 +++----
 src/backend/optimizer/plan/analyzejoins.c |  9 +++------
 src/backend/optimizer/plan/planner.c      |  1 +
 src/backend/optimizer/prep/prepjointree.c |  1 +
 src/include/nodes/pathnodes.h             |  5 ++---
 src/include/optimizer/geqo.h              | 12 +++++++++++-
 8 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/src/backend/optimizer/geqo/geqo_eval.c b/src/backend/optimizer/geqo/geqo_eval.c
index f07d1dc8ac6..7fcb1aa70d1 100644
--- a/src/backend/optimizer/geqo/geqo_eval.c
+++ b/src/backend/optimizer/geqo/geqo_eval.c
@@ -162,7 +162,7 @@ geqo_eval(PlannerInfo *root, Gene *tour, int num_gene)
 RelOptInfo *
 gimme_tree(PlannerInfo *root, Gene *tour, int num_gene)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 	List	   *clumps;
 	int			rel_count;
 
diff --git a/src/backend/optimizer/geqo/geqo_main.c b/src/backend/optimizer/geqo/geqo_main.c
index 38402ce58db..0064556087a 100644
--- a/src/backend/optimizer/geqo/geqo_main.c
+++ b/src/backend/optimizer/geqo/geqo_main.c
@@ -47,6 +47,8 @@ int			Geqo_generations;
 double		Geqo_selection_bias;
 double		Geqo_seed;
 
+/* GEQO is treated as an in-core planner extension */
+int			Geqo_planner_extension_id = -1;
 
 static int	gimme_pool_size(int nr_rel);
 static int	gimme_number_generations(int pool_size);
@@ -98,10 +100,16 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	int			mutations = 0;
 #endif
 
+	if (Geqo_planner_extension_id < 0)
+		Geqo_planner_extension_id = GetPlannerExtensionId("geqo");
+
 /* set up private information */
-	root->join_search_private = &private;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, &private);
 	private.initial_rels = initial_rels;
 
+/* inform core planner that we may replan */
+	root->assumeReplanning = true;
+
 /* initialize private number generator */
 	geqo_set_seed(root, Geqo_seed);
 
@@ -304,7 +312,7 @@ geqo(PlannerInfo *root, int number_of_rels, List *initial_rels)
 	free_pool(root, pool);
 
 	/* ... clear root pointer to our private storage */
-	root->join_search_private = NULL;
+	SetPlannerInfoExtensionState(root, Geqo_planner_extension_id, NULL);
 
 	return best_rel;
 }
diff --git a/src/backend/optimizer/geqo/geqo_random.c b/src/backend/optimizer/geqo/geqo_random.c
index 6c7a411f69f..46d28baa2e6 100644
--- a/src/backend/optimizer/geqo/geqo_random.c
+++ b/src/backend/optimizer/geqo/geqo_random.c
@@ -15,11 +15,10 @@
 
 #include "optimizer/geqo_random.h"
 
-
 void
 geqo_set_seed(PlannerInfo *root, double seed)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	pg_prng_fseed(&private->random_state, seed);
 }
@@ -27,7 +26,7 @@ geqo_set_seed(PlannerInfo *root, double seed)
 double
 geqo_rand(PlannerInfo *root)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	return pg_prng_double(&private->random_state);
 }
@@ -35,7 +34,7 @@ geqo_rand(PlannerInfo *root)
 int
 geqo_randint(PlannerInfo *root, int upper, int lower)
 {
-	GeqoPrivateData *private = (GeqoPrivateData *) root->join_search_private;
+	GeqoPrivateData *private = GetGeqoPrivateData(root);
 
 	/*
 	 * In current usage, "lower" is never negative so we can just use
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 2a3dea88a94..6a3c030e8ef 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -1425,17 +1425,14 @@ innerrel_is_unique_ext(PlannerInfo *root,
 		 *
 		 * However, in normal planning mode, caching this knowledge is totally
 		 * pointless; it won't be queried again, because we build up joinrels
-		 * from smaller to larger.  It is useful in GEQO mode, where the
-		 * knowledge can be carried across successive planning attempts; and
-		 * it's likely to be useful when using join-search plugins, too. Hence
-		 * cache when join_search_private is non-NULL.  (Yeah, that's a hack,
-		 * but it seems reasonable.)
+		 * from smaller to larger.  It's only useful when using GEQO or
+		 * another planner extension that attempts planning multiple times.
 		 *
 		 * Also, allow callers to override that heuristic and force caching;
 		 * that's useful for reduce_unique_semijoins, which calls here before
 		 * the normal join search starts.
 		 */
-		if (force_cache || root->join_search_private)
+		if (force_cache || root->assumeReplanning)
 		{
 			old_context = MemoryContextSwitchTo(root->planner_cxt);
 			innerrel->non_unique_for_rels =
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 41bd8353430..9de39da1757 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -703,6 +703,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse, PlannerInfo *parent_root,
 	root->hasAlternativeSubPlans = false;
 	root->placeholdersFrozen = false;
 	root->hasRecursion = hasRecursion;
+	root->assumeReplanning = false;
 	if (hasRecursion)
 		root->wt_param_id = assign_special_exec_param(root);
 	else
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 35e8d3c183b..4075f7519ca 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -1383,6 +1383,7 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
 	subroot->qual_security_level = 0;
 	subroot->placeholdersFrozen = false;
 	subroot->hasRecursion = false;
+	subroot->assumeReplanning = false;
 	subroot->wt_param_id = -1;
 	subroot->non_recursive_path = NULL;
 	/* We don't currently need a top JoinDomain for the subroot */
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index 5cf23cba596..bc1e0c1b5cc 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -530,6 +530,8 @@ struct PlannerInfo
 	bool		placeholdersFrozen;
 	/* true if planning a recursive WITH item */
 	bool		hasRecursion;
+	/* true if a planner extension may replan this subquery */
+	bool		assumeReplanning;
 
 	/*
 	 * The rangetable index for the RTE_GROUP RTE, or 0 if there is no
@@ -576,9 +578,6 @@ struct PlannerInfo
 	bool	   *isAltSubplan pg_node_attr(read_write_ignore);
 	bool	   *isUsedSubplan pg_node_attr(read_write_ignore);
 
-	/* optional private data for join_search_hook, e.g., GEQO */
-	void	   *join_search_private pg_node_attr(read_write_ignore);
-
 	/* Does this query modify any partition key columns? */
 	bool		partColsUpdated;
 
diff --git a/src/include/optimizer/geqo.h b/src/include/optimizer/geqo.h
index 9f8e0f337aa..b3017dd8ec4 100644
--- a/src/include/optimizer/geqo.h
+++ b/src/include/optimizer/geqo.h
@@ -24,6 +24,7 @@
 
 #include "common/pg_prng.h"
 #include "nodes/pathnodes.h"
+#include "optimizer/extendplan.h"
 #include "optimizer/geqo_gene.h"
 
 
@@ -62,6 +63,8 @@ extern PGDLLIMPORT int Geqo_generations;	/* 1 .. inf, or 0 to use default */
 
 extern PGDLLIMPORT double Geqo_selection_bias;
 
+extern PGDLLIMPORT int Geqo_planner_extension_id;
+
 #define DEFAULT_GEQO_SELECTION_BIAS 2.0
 #define MIN_GEQO_SELECTION_BIAS 1.5
 #define MAX_GEQO_SELECTION_BIAS 2.0
@@ -70,7 +73,7 @@ extern PGDLLIMPORT double Geqo_seed;	/* 0 .. 1 */
 
 
 /*
- * Private state for a GEQO run --- accessible via root->join_search_private
+ * Private state for a GEQO run --- accessible via GetGeqoPrivateData
  */
 typedef struct
 {
@@ -78,6 +81,13 @@ typedef struct
 	pg_prng_state random_state; /* PRNG state */
 } GeqoPrivateData;
 
+static inline GeqoPrivateData *
+GetGeqoPrivateData(PlannerInfo *root)
+{
+	/* headers must be C++-compliant, so the cast is required here */
+	return (GeqoPrivateData *)
+		GetPlannerInfoExtensionState(root, Geqo_planner_extension_id);
+}
 
 /* routines in geqo_main.c */
 extern RelOptInfo *geqo(PlannerInfo *root,
-- 
2.39.5 (Apple Git-154)

From c8d9a04dc2f04b7d520bc747b839c3f7e9b0683e Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 24 Sep 2025 11:18:12 -0400
Subject: [PATCH v7 3/6] Add ExplainState argument to pg_plan_query() and
 planner().

This allows extensions to have access to any data they've stored
in the ExplainState during planning. Unfortunately, it won't help
with EXPLAIN EXECUTE is used, but since that case is less common,
this still seems like an improvement.
---
 contrib/pg_stat_statements/pg_stat_statements.c    | 14 ++++++++------
 src/backend/commands/copyto.c                      |  2 +-
 src/backend/commands/createas.c                    |  2 +-
 src/backend/commands/explain.c                     |  2 +-
 src/backend/commands/matview.c                     |  2 +-
 src/backend/commands/portalcmds.c                  |  3 ++-
 src/backend/optimizer/plan/planner.c               | 10 ++++++----
 src/backend/tcop/postgres.c                        |  7 ++++---
 src/include/optimizer/optimizer.h                  |  5 ++++-
 src/include/optimizer/planner.h                    |  8 ++++++--
 src/include/tcop/tcopprot.h                        |  4 +++-
 src/test/modules/delay_execution/delay_execution.c |  7 ++++---
 12 files changed, 41 insertions(+), 25 deletions(-)

diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 0bb0f933399..d6af2f8efbf 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -337,7 +337,8 @@ static void pgss_post_parse_analyze(ParseState *pstate, Query *query,
 static PlannedStmt *pgss_planner(Query *parse,
 								 const char *query_string,
 								 int cursorOptions,
-								 ParamListInfo boundParams);
+								 ParamListInfo boundParams,
+								 ExplainState *es);
 static void pgss_ExecutorStart(QueryDesc *queryDesc, int eflags);
 static void pgss_ExecutorRun(QueryDesc *queryDesc,
 							 ScanDirection direction,
@@ -893,7 +894,8 @@ static PlannedStmt *
 pgss_planner(Query *parse,
 			 const char *query_string,
 			 int cursorOptions,
-			 ParamListInfo boundParams)
+			 ParamListInfo boundParams,
+			 ExplainState *es)
 {
 	PlannedStmt *result;
 
@@ -928,10 +930,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
@@ -977,10 +979,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
diff --git a/src/backend/commands/copyto.c b/src/backend/commands/copyto.c
index 67b94b91cae..e5781155cdf 100644
--- a/src/backend/commands/copyto.c
+++ b/src/backend/commands/copyto.c
@@ -796,7 +796,7 @@ BeginCopyTo(ParseState *pstate,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, NULL);
+							 CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 		/*
 		 * With row-level security and a user using "COPY relation TO", we
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1ccc2e55c64 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -321,7 +321,7 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, params);
+							 CURSOR_OPT_PARALLEL_OK, params, NULL);
 
 		/*
 		 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 207f86f1d39..82d14db8d68 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -351,7 +351,7 @@ standard_ExplainOneQuery(Query *query, int cursorOptions,
 	INSTR_TIME_SET_CURRENT(planstart);
 
 	/* plan the query */
-	plan = pg_plan_query(query, queryString, cursorOptions, params);
+	plan = pg_plan_query(query, queryString, cursorOptions, params, es);
 
 	INSTR_TIME_SET_CURRENT(planduration);
 	INSTR_TIME_SUBTRACT(planduration, planstart);
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 188e26f0e6e..441de55ac24 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -426,7 +426,7 @@ refresh_matview_datafill(DestReceiver *dest, Query *query,
 	CHECK_FOR_INTERRUPTS();
 
 	/* Plan the query which will generate data for the refresh. */
-	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL);
+	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 	/*
 	 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c
index e7c8171c102..ec96c2efcd3 100644
--- a/src/backend/commands/portalcmds.c
+++ b/src/backend/commands/portalcmds.c
@@ -99,7 +99,8 @@ PerformCursorOpen(ParseState *pstate, DeclareCursorStmt *cstmt, ParamListInfo pa
 		elog(ERROR, "non-SELECT statement in DECLARE CURSOR");
 
 	/* Plan the query, applying the specified options */
-	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params);
+	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params,
+						 NULL);
 
 	/*
 	 * Create a portal and copy the plan and query string into its memory.
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 9de39da1757..205d8886a2a 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -291,14 +291,16 @@ static void create_partial_unique_paths(PlannerInfo *root, RelOptInfo *input_rel
  *****************************************************************************/
 PlannedStmt *
 planner(Query *parse, const char *query_string, int cursorOptions,
-		ParamListInfo boundParams)
+		ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 
 	if (planner_hook)
-		result = (*planner_hook) (parse, query_string, cursorOptions, boundParams);
+		result = (*planner_hook) (parse, query_string, cursorOptions,
+								  boundParams, es);
 	else
-		result = standard_planner(parse, query_string, cursorOptions, boundParams);
+		result = standard_planner(parse, query_string, cursorOptions,
+								  boundParams, es);
 
 	pgstat_report_plan_id(result->planId, false);
 
@@ -307,7 +309,7 @@ planner(Query *parse, const char *query_string, int cursorOptions,
 
 PlannedStmt *
 standard_planner(Query *parse, const char *query_string, int cursorOptions,
-				 ParamListInfo boundParams)
+				 ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 	PlannerGlobal *glob;
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index d356830f756..7dd75a490aa 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -37,6 +37,7 @@
 #include "catalog/pg_type.h"
 #include "commands/async.h"
 #include "commands/event_trigger.h"
+#include "commands/explain_state.h"
 #include "commands/prepare.h"
 #include "common/pg_prng.h"
 #include "jit/jit.h"
@@ -884,7 +885,7 @@ pg_rewrite_query(Query *query)
  */
 PlannedStmt *
 pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
-			  ParamListInfo boundParams)
+			  ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *plan;
 
@@ -901,7 +902,7 @@ pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
 		ResetUsage();
 
 	/* call the optimizer */
-	plan = planner(querytree, query_string, cursorOptions, boundParams);
+	plan = planner(querytree, query_string, cursorOptions, boundParams, es);
 
 	if (log_planner_stats)
 		ShowUsage("PLANNER STATISTICS");
@@ -997,7 +998,7 @@ pg_plan_queries(List *querytrees, const char *query_string, int cursorOptions,
 		else
 		{
 			stmt = pg_plan_query(query, query_string, cursorOptions,
-								 boundParams);
+								 boundParams, NULL);
 		}
 
 		stmt_list = lappend(stmt_list, stmt);
diff --git a/src/include/optimizer/optimizer.h b/src/include/optimizer/optimizer.h
index 04878f1f1c2..a34113903c0 100644
--- a/src/include/optimizer/optimizer.h
+++ b/src/include/optimizer/optimizer.h
@@ -24,6 +24,8 @@
 
 #include "nodes/parsenodes.h"
 
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
+
 /*
  * We don't want to include nodes/pathnodes.h here, because non-planner
  * code should generally treat PlannerInfo as an opaque typedef.
@@ -104,7 +106,8 @@ extern PGDLLIMPORT bool enable_distinct_reordering;
 
 extern PlannedStmt *planner(Query *parse, const char *query_string,
 							int cursorOptions,
-							ParamListInfo boundParams);
+							ParamListInfo boundParams,
+							ExplainState *es);
 
 extern Expr *expression_planner(Expr *expr);
 extern Expr *expression_planner_with_deps(Expr *expr,
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index f220e9a270d..b31ea2fbbdc 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -22,11 +22,14 @@
 #include "nodes/plannodes.h"
 
 
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
+
 /* Hook for plugins to get control in planner() */
 typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   const char *query_string,
 										   int cursorOptions,
-										   ParamListInfo boundParams);
+										   ParamListInfo boundParams,
+										   ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
@@ -40,7 +43,8 @@ extern PGDLLIMPORT create_upper_paths_hook_type create_upper_paths_hook;
 
 extern PlannedStmt *standard_planner(Query *parse, const char *query_string,
 									 int cursorOptions,
-									 ParamListInfo boundParams);
+									 ParamListInfo boundParams,
+									 ExplainState *es);
 
 extern PlannerInfo *subquery_planner(PlannerGlobal *glob, Query *parse,
 									 PlannerInfo *parent_root,
diff --git a/src/include/tcop/tcopprot.h b/src/include/tcop/tcopprot.h
index a83cc4f4850..c1bcfdec673 100644
--- a/src/include/tcop/tcopprot.h
+++ b/src/include/tcop/tcopprot.h
@@ -20,6 +20,7 @@
 #include "utils/guc.h"
 #include "utils/queryenvironment.h"
 
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
 
 extern PGDLLIMPORT CommandDest whereToSendOutput;
 extern PGDLLIMPORT const char *debug_query_string;
@@ -63,7 +64,8 @@ extern List *pg_analyze_and_rewrite_withcb(RawStmt *parsetree,
 										   QueryEnvironment *queryEnv);
 extern PlannedStmt *pg_plan_query(Query *querytree, const char *query_string,
 								  int cursorOptions,
-								  ParamListInfo boundParams);
+								  ParamListInfo boundParams,
+								  ExplainState *es);
 extern List *pg_plan_queries(List *querytrees, const char *query_string,
 							 int cursorOptions,
 							 ParamListInfo boundParams);
diff --git a/src/test/modules/delay_execution/delay_execution.c b/src/test/modules/delay_execution/delay_execution.c
index 7bc97f84a1c..d933e9a6e53 100644
--- a/src/test/modules/delay_execution/delay_execution.c
+++ b/src/test/modules/delay_execution/delay_execution.c
@@ -40,17 +40,18 @@ static planner_hook_type prev_planner_hook = NULL;
 /* planner_hook function to provide the desired delay */
 static PlannedStmt *
 delay_execution_planner(Query *parse, const char *query_string,
-						int cursorOptions, ParamListInfo boundParams)
+						int cursorOptions, ParamListInfo boundParams,
+						ExplainState *es)
 {
 	PlannedStmt *result;
 
 	/* Invoke the planner, possibly via a previous hook user */
 	if (prev_planner_hook)
 		result = prev_planner_hook(parse, query_string, cursorOptions,
-								   boundParams);
+								   boundParams, es);
 	else
 		result = standard_planner(parse, query_string, cursorOptions,
-								  boundParams);
+								  boundParams, es);
 
 	/* If enabled, delay by taking and releasing the specified lock */
 	if (post_planning_lock_id != 0)
-- 
2.39.5 (Apple Git-154)

From 859ad61547be85695a17158249ec3cad2710b018 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 14:29:02 -0400
Subject: [PATCH v7 5/6] Add extension_state member to PlannedStmt.

Extensions can stash data computed at plan time into this list using
planner_shutdown_hook (or perhaps other mechanisms) and then access
it from any code that has access to the PlannedStmt (such as explain
hooks), allowing for extensible debugging and instrumentation of
plans.
---
 src/include/nodes/plannodes.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 3d196f5078e..77ec2bc10b2 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -149,6 +149,15 @@ typedef struct PlannedStmt
 	/* non-null if this is utility stmt */
 	Node	   *utilityStmt;
 
+	/*
+	 * DefElem objects added by extensions, e.g. using planner_shutdown_hook
+	 *
+	 * Set each DefElem's defname to the name of the plugin or extension, and
+	 * the argument to a tree of nodes that all have copy and read/write
+	 * support.
+	 */
+	List	   *extension_state;
+
 	/* statement location in source string (copied from Query) */
 	/* start location, or -1 if unknown */
 	ParseLoc	stmt_location;
-- 
2.39.5 (Apple Git-154)

From a35f6e8367dfd96ea79b60b82c742e203f534422 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 15:22:57 -0400
Subject: [PATCH v7 6/6] not for commit: count distinct joinrels and joinrel
 planning attempts

---
 .../expected/pg_overexplain.out               |  22 ++-
 contrib/pg_overexplain/pg_overexplain.c       | 125 ++++++++++++++++++
 2 files changed, 142 insertions(+), 5 deletions(-)

diff --git a/contrib/pg_overexplain/expected/pg_overexplain.out b/contrib/pg_overexplain/expected/pg_overexplain.out
index 55d34666d87..48251298f05 100644
--- a/contrib/pg_overexplain/expected/pg_overexplain.out
+++ b/contrib/pg_overexplain/expected/pg_overexplain.out
@@ -38,7 +38,9 @@ EXPLAIN (DEBUG) SELECT 1;
    Relation OIDs: none
    Executor Parameter Types: none
    Parse Location: 0 to end
-(11 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(13 rows)
 
 EXPLAIN (RANGE_TABLE) SELECT 1;
                 QUERY PLAN                
@@ -121,6 +123,8 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
  RTI 1 (relation, inherited, in-from-clause):
    Eref: vegetables (id, name, genus)
    Relation: vegetables
@@ -142,7 +146,7 @@ $$);
    Relation Kind: relation
    Relation Lock Mode: AccessShareLock
  Unprunable RTIs: 1 3 4
-(53 rows)
+(55 rows)
 
 -- Test a different output format.
 SELECT explain_filter($$
@@ -242,6 +246,8 @@ $$);
        <Relation-OIDs>NNN...</Relation-OIDs>                        +
        <Executor-Parameter-Types>none</Executor-Parameter-Types>    +
        <Parse-Location>0 to end</Parse-Location>                    +
+       <Total-Joinrel-Attempts>0</Total-Joinrel-Attempts>           +
+       <Distinct-Joinrels>0</Distinct-Joinrels>                     +
      </PlannedStmt>                                                 +
      <Range-Table>                                                  +
        <Range-Table-Entry>                                          +
@@ -346,7 +352,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: none
    Parse Location: 0 to end
-(37 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(39 rows)
 
 SET debug_parallel_query = false;
 RESET enable_seqscan;
@@ -374,7 +382,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 0
    Parse Location: 0 to end
-(15 rows)
+   Total Joinrel Attempts: 0
+   Distinct Joinrels: 0
+(17 rows)
 
 -- Create an index, and then attempt to force a nested loop with inner index
 -- scan so that we can see parameter-related information. Also, let's try
@@ -438,7 +448,9 @@ $$);
    Relation OIDs: NNN...
    Executor Parameter Types: 23
    Parse Location: 0 to end
-(47 rows)
+   Total Joinrel Attempts: 2
+   Distinct Joinrels: 1
+(49 rows)
 
 RESET enable_hashjoin;
 RESET enable_material;
diff --git a/contrib/pg_overexplain/pg_overexplain.c b/contrib/pg_overexplain/pg_overexplain.c
index bd70b6d9d5e..93d2051f4fb 100644
--- a/contrib/pg_overexplain/pg_overexplain.c
+++ b/contrib/pg_overexplain/pg_overexplain.c
@@ -16,6 +16,10 @@
 #include "commands/explain_format.h"
 #include "commands/explain_state.h"
 #include "fmgr.h"
+#include "nodes/makefuncs.h"
+#include "optimizer/extendplan.h"
+#include "optimizer/paths.h"
+#include "optimizer/planner.h"
 #include "parser/parsetree.h"
 #include "storage/lock.h"
 #include "utils/builtins.h"
@@ -32,6 +36,12 @@ typedef struct
 	bool		range_table;
 } overexplain_options;
 
+typedef struct
+{
+	int			total_joinrel_attempts;
+	int			distinct_joinrel_count;
+} overexplain_plannerglobal;
+
 static overexplain_options *overexplain_ensure_options(ExplainState *es);
 static void overexplain_debug_handler(ExplainState *es, DefElem *opt,
 									  ParseState *pstate);
@@ -57,9 +67,28 @@ static void overexplain_bitmapset(const char *qlabel, Bitmapset *bms,
 static void overexplain_intlist(const char *qlabel, List *list,
 								ExplainState *es);
 
+static void overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+										   const char *query_string,
+										   double *tuple_fraction,
+										   struct ExplainState *es);
+static void overexplain_planner_shutdown_hook(PlannerGlobal *glob,
+											  Query *parse,
+											  const char *query_string,
+											  PlannedStmt *pstmt);
+static void overexplain_set_join_pathlist_hook(PlannerInfo *root,
+											   RelOptInfo *joinrel,
+											   RelOptInfo *outerrel,
+											   RelOptInfo *innerrel,
+											   JoinType jointype,
+											   JoinPathExtraData *extra);
+
 static int	es_extension_id;
+static int	planner_extension_id = -1;
 static explain_per_node_hook_type prev_explain_per_node_hook;
 static explain_per_plan_hook_type prev_explain_per_plan_hook;
+static planner_setup_hook_type prev_planner_setup_hook;
+static planner_shutdown_hook_type prev_planner_shutdown_hook;
+static set_join_pathlist_hook_type prev_set_join_pathlist_hook;
 
 /*
  * Initialization we do when this module is loaded.
@@ -70,6 +99,9 @@ _PG_init(void)
 	/* Get an ID that we can use to cache data in an ExplainState. */
 	es_extension_id = GetExplainExtensionId("pg_overexplain");
 
+	/* Get an ID that we can use to cache data in the planner. */
+	planner_extension_id = GetPlannerExtensionId("pg_overexplain");
+
 	/* Register the new EXPLAIN options implemented by this module. */
 	RegisterExtensionExplainOption("debug", overexplain_debug_handler);
 	RegisterExtensionExplainOption("range_table",
@@ -80,6 +112,16 @@ _PG_init(void)
 	explain_per_node_hook = overexplain_per_node_hook;
 	prev_explain_per_plan_hook = explain_per_plan_hook;
 	explain_per_plan_hook = overexplain_per_plan_hook;
+
+	/* Example of planner_setup_hook/planner_shutdown_hook use */
+	prev_planner_setup_hook = planner_setup_hook;
+	planner_setup_hook = overexplain_planner_setup_hook;
+	prev_planner_shutdown_hook = planner_shutdown_hook;
+	planner_shutdown_hook = overexplain_planner_shutdown_hook;
+
+	/* Support for above example */
+	prev_set_join_pathlist_hook = set_join_pathlist_hook;
+	set_join_pathlist_hook = overexplain_set_join_pathlist_hook;
 }
 
 /*
@@ -381,6 +423,29 @@ overexplain_debug(PlannedStmt *plannedstmt, ExplainState *es)
 									 plannedstmt->stmt_len),
 							es);
 
+	{
+		DefElem    *elem = NULL;
+
+		foreach_node(DefElem, de, plannedstmt->extension_state)
+		{
+			if (strcmp(de->defname, "pg_overexplain") == 0)
+			{
+				elem = de;
+				break;
+			}
+		}
+
+		if (elem != NULL)
+		{
+			List	   *l = castNode(List, elem->arg);
+
+			ExplainPropertyInteger("Total Joinrel Attempts", NULL,
+								   intVal(linitial(l)), es);
+			ExplainPropertyInteger("Distinct Joinrels", NULL,
+								   intVal(lsecond(l)), es);
+		}
+	}
+
 	/* Done with this group. */
 	if (es->format == EXPLAIN_FORMAT_TEXT)
 		es->indent--;
@@ -784,3 +849,63 @@ overexplain_intlist(const char *qlabel, List *list, ExplainState *es)
 
 	pfree(buf.data);
 }
+
+static void
+overexplain_planner_setup_hook(PlannerGlobal *glob, Query *parse,
+							   const char *query_string,
+							   double *tuple_fraction,
+							   struct ExplainState *es)
+{
+	overexplain_options *options;
+	overexplain_plannerglobal *g;
+
+	if (es != NULL)
+	{
+		options = GetExplainExtensionState(es, es_extension_id);
+		if (options != NULL && options->debug)
+		{
+			g = palloc0_object(overexplain_plannerglobal);
+			SetPlannerGlobalExtensionState(glob, planner_extension_id, g);
+		}
+	}
+}
+
+static void
+overexplain_planner_shutdown_hook(PlannerGlobal *glob, Query *parse,
+								  const char *query_string, PlannedStmt *pstmt)
+{
+	overexplain_plannerglobal *g;
+	DefElem    *elem;
+	List	   *l;
+
+	g = GetPlannerGlobalExtensionState(glob, planner_extension_id);
+	if (g != NULL)
+	{
+		l = list_make2(makeInteger(g->total_joinrel_attempts),
+					   makeInteger(g->distinct_joinrel_count));
+		elem = makeDefElem("pg_overexplain", (Node *) l, -1);
+		pstmt->extension_state = lappend(pstmt->extension_state, elem);
+	}
+}
+
+static void
+overexplain_set_join_pathlist_hook(PlannerInfo *root, RelOptInfo *joinrel,
+								   RelOptInfo *outerrel, RelOptInfo *innerrel,
+								   JoinType jointype, JoinPathExtraData *extra)
+{
+	overexplain_plannerglobal *g;
+
+	g = GetPlannerGlobalExtensionState(root->glob, planner_extension_id);
+
+	if (g != NULL)
+	{
+		g->total_joinrel_attempts++;
+
+		if (GetRelOptInfoExtensionState(joinrel, planner_extension_id) == NULL)
+		{
+			g->distinct_joinrel_count++;
+			/* set any non-NULL value to avoid double-counting */
+			SetRelOptInfoExtensionState(joinrel, planner_extension_id, g);
+		}
+	}
+}
-- 
2.39.5 (Apple Git-154)

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 41bd8353430..c249f34eb8e 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -280,6 +280,23 @@ static void create_partial_unique_paths(PlannerInfo *root, RelOptInfo *input_rel
  *
  *	   Query optimizer entry point
  *
+ * Inputs:
+ *	parse: an analyzed-and-rewritten query tree for an optimizable statement
+ *	query_string: source text for the query tree (used for error reports)
+ *	cursorOptions: bitmask of CURSOR_OPT_XXX flags, see parsenodes.h
+ *	boundParams: passed-in parameter values, or NULL if none
+ *	es: ExplainState if being called from EXPLAIN, else NULL
+ *
+ * The result is a PlannedStmt tree.
+ *
+ * PARAM_EXTERN Param nodes within the parse tree can be replaced by Consts
+ * using values from boundParams, if those values are marked PARAM_FLAG_CONST.
+ * Parameter values not so marked are still relied on for estimation purposes.
+ *
+ * The ExplainState pointer is not currently used by the core planner, but it
+ * is passed through to some planner hooks so that they can report information
+ * back to EXPLAIN extension hooks.
+ *
  * To support loadable plugins that monitor or modify planner behavior,
  * we provide a hook variable that lets a plugin get control before and
  * after the standard planning process.  The plugin would normally call

From a417152e17f5a5fdba8acb9404a3a2079c83efd8 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 24 Sep 2025 11:18:12 -0400
Subject: [PATCH v8 1/3] Add ExplainState argument to pg_plan_query() and
 planner().

This allows extensions to have access to any data they've stored
in the ExplainState during planning. Unfortunately, it won't help
with EXPLAIN EXECUTE is used, but since that case is less common,
this still seems like an improvement.

Since planner() has quite a few arguments now, also add some
documentation of those arguments and the return value.

Author: Robert Haas <rhaas@postgresql.org>
Co-authored-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Andrei Lepikhov <lepihov@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: http://postgr.es/m/CA+TgmoYWKHU2hKr62Toyzh-kTDEnMDeLw7gkOOnjL-TnOUq0kQ@mail.gmail.com
---
 .../pg_stat_statements/pg_stat_statements.c   | 14 +++++-----
 src/backend/commands/copyto.c                 |  2 +-
 src/backend/commands/createas.c               |  2 +-
 src/backend/commands/explain.c                |  2 +-
 src/backend/commands/matview.c                |  2 +-
 src/backend/commands/portalcmds.c             |  3 ++-
 src/backend/optimizer/plan/planner.c          | 27 ++++++++++++++++---
 src/backend/tcop/postgres.c                   |  7 ++---
 src/include/optimizer/optimizer.h             |  5 +++-
 src/include/optimizer/planner.h               |  8 ++++--
 src/include/tcop/tcopprot.h                   |  4 ++-
 .../modules/delay_execution/delay_execution.c |  7 ++---
 12 files changed, 58 insertions(+), 25 deletions(-)

diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index db1af36a705..f2187167c5c 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -338,7 +338,8 @@ static void pgss_post_parse_analyze(ParseState *pstate, Query *query,
 static PlannedStmt *pgss_planner(Query *parse,
 								 const char *query_string,
 								 int cursorOptions,
-								 ParamListInfo boundParams);
+								 ParamListInfo boundParams,
+								 ExplainState *es);
 static void pgss_ExecutorStart(QueryDesc *queryDesc, int eflags);
 static void pgss_ExecutorRun(QueryDesc *queryDesc,
 							 ScanDirection direction,
@@ -894,7 +895,8 @@ static PlannedStmt *
 pgss_planner(Query *parse,
 			 const char *query_string,
 			 int cursorOptions,
-			 ParamListInfo boundParams)
+			 ParamListInfo boundParams,
+			 ExplainState *es)
 {
 	PlannedStmt *result;
 
@@ -929,10 +931,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
@@ -978,10 +980,10 @@ pgss_planner(Query *parse,
 		{
 			if (prev_planner_hook)
 				result = prev_planner_hook(parse, query_string, cursorOptions,
-										   boundParams);
+										   boundParams, es);
 			else
 				result = standard_planner(parse, query_string, cursorOptions,
-										  boundParams);
+										  boundParams, es);
 		}
 		PG_FINALLY();
 		{
diff --git a/src/backend/commands/copyto.c b/src/backend/commands/copyto.c
index 67b94b91cae..e5781155cdf 100644
--- a/src/backend/commands/copyto.c
+++ b/src/backend/commands/copyto.c
@@ -796,7 +796,7 @@ BeginCopyTo(ParseState *pstate,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, NULL);
+							 CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 		/*
 		 * With row-level security and a user using "COPY relation TO", we
diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index dfd2ab8e862..1ccc2e55c64 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -321,7 +321,7 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
 
 		/* plan the query */
 		plan = pg_plan_query(query, pstate->p_sourcetext,
-							 CURSOR_OPT_PARALLEL_OK, params);
+							 CURSOR_OPT_PARALLEL_OK, params, NULL);
 
 		/*
 		 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 06191cd8a85..e6edae0845c 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -351,7 +351,7 @@ standard_ExplainOneQuery(Query *query, int cursorOptions,
 	INSTR_TIME_SET_CURRENT(planstart);
 
 	/* plan the query */
-	plan = pg_plan_query(query, queryString, cursorOptions, params);
+	plan = pg_plan_query(query, queryString, cursorOptions, params, es);
 
 	INSTR_TIME_SET_CURRENT(planduration);
 	INSTR_TIME_SUBTRACT(planduration, planstart);
diff --git a/src/backend/commands/matview.c b/src/backend/commands/matview.c
index 188e26f0e6e..441de55ac24 100644
--- a/src/backend/commands/matview.c
+++ b/src/backend/commands/matview.c
@@ -426,7 +426,7 @@ refresh_matview_datafill(DestReceiver *dest, Query *query,
 	CHECK_FOR_INTERRUPTS();
 
 	/* Plan the query which will generate data for the refresh. */
-	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL);
+	plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL, NULL);
 
 	/*
 	 * Use a snapshot with an updated command ID to ensure this query sees
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c
index e7c8171c102..ec96c2efcd3 100644
--- a/src/backend/commands/portalcmds.c
+++ b/src/backend/commands/portalcmds.c
@@ -99,7 +99,8 @@ PerformCursorOpen(ParseState *pstate, DeclareCursorStmt *cstmt, ParamListInfo pa
 		elog(ERROR, "non-SELECT statement in DECLARE CURSOR");
 
 	/* Plan the query, applying the specified options */
-	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params);
+	plan = pg_plan_query(query, pstate->p_sourcetext, cstmt->options, params,
+						 NULL);
 
 	/*
 	 * Create a portal and copy the plan and query string into its memory.
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 0c9397a36c3..8d1d45eab8d 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -280,6 +280,23 @@ static void create_partial_unique_paths(PlannerInfo *root, RelOptInfo *input_rel
  *
  *	   Query optimizer entry point
  *
+ * Inputs:
+ *	parse: an analyzed-and-rewritten query tree for an optimizable statement
+ *	query_string: source text for the query tree (used for error reports)
+ *	cursorOptions: bitmask of CURSOR_OPT_XXX flags, see parsenodes.h
+ *	boundParams: passed-in parameter values, or NULL if none
+ *	es: ExplainState if being called from EXPLAIN, else NULL
+ *
+ * The result is a PlannedStmt tree.
+ *
+ * PARAM_EXTERN Param nodes within the parse tree can be replaced by Consts
+ * using values from boundParams, if those values are marked PARAM_FLAG_CONST.
+ * Parameter values not so marked are still relied on for estimation purposes.
+ *
+ * The ExplainState pointer is not currently used by the core planner, but it
+ * is passed through to some planner hooks so that they can report information
+ * back to EXPLAIN extension hooks.
+ *
  * To support loadable plugins that monitor or modify planner behavior,
  * we provide a hook variable that lets a plugin get control before and
  * after the standard planning process.  The plugin would normally call
@@ -291,14 +308,16 @@ static void create_partial_unique_paths(PlannerInfo *root, RelOptInfo *input_rel
  *****************************************************************************/
 PlannedStmt *
 planner(Query *parse, const char *query_string, int cursorOptions,
-		ParamListInfo boundParams)
+		ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 
 	if (planner_hook)
-		result = (*planner_hook) (parse, query_string, cursorOptions, boundParams);
+		result = (*planner_hook) (parse, query_string, cursorOptions,
+								  boundParams, es);
 	else
-		result = standard_planner(parse, query_string, cursorOptions, boundParams);
+		result = standard_planner(parse, query_string, cursorOptions,
+								  boundParams, es);
 
 	pgstat_report_plan_id(result->planId, false);
 
@@ -307,7 +326,7 @@ planner(Query *parse, const char *query_string, int cursorOptions,
 
 PlannedStmt *
 standard_planner(Query *parse, const char *query_string, int cursorOptions,
-				 ParamListInfo boundParams)
+				 ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *result;
 	PlannerGlobal *glob;
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index d356830f756..7dd75a490aa 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -37,6 +37,7 @@
 #include "catalog/pg_type.h"
 #include "commands/async.h"
 #include "commands/event_trigger.h"
+#include "commands/explain_state.h"
 #include "commands/prepare.h"
 #include "common/pg_prng.h"
 #include "jit/jit.h"
@@ -884,7 +885,7 @@ pg_rewrite_query(Query *query)
  */
 PlannedStmt *
 pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
-			  ParamListInfo boundParams)
+			  ParamListInfo boundParams, ExplainState *es)
 {
 	PlannedStmt *plan;
 
@@ -901,7 +902,7 @@ pg_plan_query(Query *querytree, const char *query_string, int cursorOptions,
 		ResetUsage();
 
 	/* call the optimizer */
-	plan = planner(querytree, query_string, cursorOptions, boundParams);
+	plan = planner(querytree, query_string, cursorOptions, boundParams, es);
 
 	if (log_planner_stats)
 		ShowUsage("PLANNER STATISTICS");
@@ -997,7 +998,7 @@ pg_plan_queries(List *querytrees, const char *query_string, int cursorOptions,
 		else
 		{
 			stmt = pg_plan_query(query, query_string, cursorOptions,
-								 boundParams);
+								 boundParams, NULL);
 		}
 
 		stmt_list = lappend(stmt_list, stmt);
diff --git a/src/include/optimizer/optimizer.h b/src/include/optimizer/optimizer.h
index 04878f1f1c2..a34113903c0 100644
--- a/src/include/optimizer/optimizer.h
+++ b/src/include/optimizer/optimizer.h
@@ -24,6 +24,8 @@
 
 #include "nodes/parsenodes.h"
 
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
+
 /*
  * We don't want to include nodes/pathnodes.h here, because non-planner
  * code should generally treat PlannerInfo as an opaque typedef.
@@ -104,7 +106,8 @@ extern PGDLLIMPORT bool enable_distinct_reordering;
 
 extern PlannedStmt *planner(Query *parse, const char *query_string,
 							int cursorOptions,
-							ParamListInfo boundParams);
+							ParamListInfo boundParams,
+							ExplainState *es);
 
 extern Expr *expression_planner(Expr *expr);
 extern Expr *expression_planner_with_deps(Expr *expr,
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index 1bbef0018d5..c7ab466f5f1 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -22,11 +22,14 @@
 #include "nodes/plannodes.h"
 
 
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
+
 /* Hook for plugins to get control in planner() */
 typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   const char *query_string,
 										   int cursorOptions,
-										   ParamListInfo boundParams);
+										   ParamListInfo boundParams,
+										   ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
@@ -40,7 +43,8 @@ extern PGDLLIMPORT create_upper_paths_hook_type create_upper_paths_hook;
 
 extern PlannedStmt *standard_planner(Query *parse, const char *query_string,
 									 int cursorOptions,
-									 ParamListInfo boundParams);
+									 ParamListInfo boundParams,
+									 ExplainState *es);
 
 extern PlannerInfo *subquery_planner(PlannerGlobal *glob, Query *parse,
 									 char *plan_name,
diff --git a/src/include/tcop/tcopprot.h b/src/include/tcop/tcopprot.h
index a83cc4f4850..c1bcfdec673 100644
--- a/src/include/tcop/tcopprot.h
+++ b/src/include/tcop/tcopprot.h
@@ -20,6 +20,7 @@
 #include "utils/guc.h"
 #include "utils/queryenvironment.h"
 
+typedef struct ExplainState ExplainState;	/* defined in explain_state.h */
 
 extern PGDLLIMPORT CommandDest whereToSendOutput;
 extern PGDLLIMPORT const char *debug_query_string;
@@ -63,7 +64,8 @@ extern List *pg_analyze_and_rewrite_withcb(RawStmt *parsetree,
 										   QueryEnvironment *queryEnv);
 extern PlannedStmt *pg_plan_query(Query *querytree, const char *query_string,
 								  int cursorOptions,
-								  ParamListInfo boundParams);
+								  ParamListInfo boundParams,
+								  ExplainState *es);
 extern List *pg_plan_queries(List *querytrees, const char *query_string,
 							 int cursorOptions,
 							 ParamListInfo boundParams);
diff --git a/src/test/modules/delay_execution/delay_execution.c b/src/test/modules/delay_execution/delay_execution.c
index 7bc97f84a1c..d933e9a6e53 100644
--- a/src/test/modules/delay_execution/delay_execution.c
+++ b/src/test/modules/delay_execution/delay_execution.c
@@ -40,17 +40,18 @@ static planner_hook_type prev_planner_hook = NULL;
 /* planner_hook function to provide the desired delay */
 static PlannedStmt *
 delay_execution_planner(Query *parse, const char *query_string,
-						int cursorOptions, ParamListInfo boundParams)
+						int cursorOptions, ParamListInfo boundParams,
+						ExplainState *es)
 {
 	PlannedStmt *result;
 
 	/* Invoke the planner, possibly via a previous hook user */
 	if (prev_planner_hook)
 		result = prev_planner_hook(parse, query_string, cursorOptions,
-								   boundParams);
+								   boundParams, es);
 	else
 		result = standard_planner(parse, query_string, cursorOptions,
-								  boundParams);
+								  boundParams, es);
 
 	/* If enabled, delay by taking and releasing the specified lock */
 	if (post_planning_lock_id != 0)
-- 
2.50.1 (Apple Git-155)

From fb682e0c7587a425693e3435fb0833fc9339f525 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 25 Aug 2025 14:29:02 -0400
Subject: [PATCH v8 3/3] Add extension_state member to PlannedStmt.

Extensions can stash data computed at plan time into this list using
planner_shutdown_hook (or perhaps other mechanisms) and then access
it from any code that has access to the PlannedStmt (such as explain
hooks), allowing for extensible debugging and instrumentation of
plans.

Reviewed-by: Andrei Lepikhov <lepihov@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: http://postgr.es/m/CA+TgmoYWKHU2hKr62Toyzh-kTDEnMDeLw7gkOOnjL-TnOUq0kQ@mail.gmail.com
---
 src/include/nodes/plannodes.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 3d196f5078e..77ec2bc10b2 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -149,6 +149,15 @@ typedef struct PlannedStmt
 	/* non-null if this is utility stmt */
 	Node	   *utilityStmt;
 
+	/*
+	 * DefElem objects added by extensions, e.g. using planner_shutdown_hook
+	 *
+	 * Set each DefElem's defname to the name of the plugin or extension, and
+	 * the argument to a tree of nodes that all have copy and read/write
+	 * support.
+	 */
+	List	   *extension_state;
+
 	/* statement location in source string (copied from Query) */
 	/* start location, or -1 if unknown */
 	ParseLoc	stmt_location;
-- 
2.50.1 (Apple Git-155)

From 65ff8de84599c626d32e1485593d1b59c06f9bb3 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 24 Sep 2025 11:21:55 -0400
Subject: [PATCH v8 2/3] Add planner_setup_hook and planner_shutdown_hook.

These hooks allow plugins to get control at the earliest point at
which the PlannerGlobal object is fully initialized, and then just
before it gets destroyed. This is useful in combination with the
extendable plan state facilities (see extendplan.h) and perhaps for
other purposes as well.

Reviewed-by: Andrei Lepikhov <lepihov@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: http://postgr.es/m/CA+TgmoYWKHU2hKr62Toyzh-kTDEnMDeLw7gkOOnjL-TnOUq0kQ@mail.gmail.com
---
 src/backend/optimizer/plan/planner.c | 14 ++++++++++++++
 src/include/optimizer/planner.h      | 13 +++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 8d1d45eab8d..b3c169d2b9e 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -73,6 +73,12 @@ bool		enable_distinct_reordering = true;
 /* Hook for plugins to get control in planner() */
 planner_hook_type planner_hook = NULL;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+planner_setup_hook_type planner_setup_hook = NULL;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+planner_shutdown_hook_type planner_shutdown_hook = NULL;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 create_upper_paths_hook_type create_upper_paths_hook = NULL;
 
@@ -457,6 +463,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 		tuple_fraction = 0.0;
 	}
 
+	/* Allow plugins to take control after we've initialized "glob" */
+	if (planner_setup_hook)
+		(*planner_setup_hook) (glob, parse, query_string, &tuple_fraction, es);
+
 	/* primary planning entry point (may recurse for subqueries) */
 	root = subquery_planner(glob, parse, NULL, NULL, false, tuple_fraction,
 							NULL);
@@ -636,6 +646,10 @@ standard_planner(Query *parse, const char *query_string, int cursorOptions,
 			result->jitFlags |= PGJIT_DEFORM;
 	}
 
+	/* Allow plugins to take control before we discard "glob" */
+	if (planner_shutdown_hook)
+		(*planner_shutdown_hook) (glob, parse, query_string, result);
+
 	if (glob->partition_directory != NULL)
 		DestroyPartitionDirectory(glob->partition_directory);
 
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index c7ab466f5f1..55d9b7940aa 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -32,6 +32,19 @@ typedef PlannedStmt *(*planner_hook_type) (Query *parse,
 										   ExplainState *es);
 extern PGDLLIMPORT planner_hook_type planner_hook;
 
+/* Hook for plugins to get control after PlannerGlobal is initialized */
+typedef void (*planner_setup_hook_type) (PlannerGlobal *glob, Query *parse,
+										 const char *query_string,
+										 double *tuple_fraction,
+										 ExplainState *es);
+extern PGDLLIMPORT planner_setup_hook_type planner_setup_hook;
+
+/* Hook for plugins to get control before PlannerGlobal is discarded */
+typedef void (*planner_shutdown_hook_type) (PlannerGlobal *glob, Query *parse,
+											const char *query_string,
+											PlannedStmt *pstmt);
+extern PGDLLIMPORT planner_shutdown_hook_type planner_shutdown_hook;
+
 /* Hook for plugins to get control when grouping_planner() plans upper rels */
 typedef void (*create_upper_paths_hook_type) (PlannerInfo *root,
 											  UpperRelationKind stage,
-- 
2.50.1 (Apple Git-155)