4 files changed, 48 insertions, 19 deletions

diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index cc9705d06bf..d447bc9b436 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -549,6 +549,7 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 	{
 		MemoryContext col_context,
 					old_context;
+		bool		build_ext_stats;
 
 		pgstat_progress_update_param(PROGRESS_ANALYZE_PHASE,
 									 PROGRESS_ANALYZE_PHASE_COMPUTE_STATS);
@@ -613,12 +614,27 @@ do_analyze_rel(Relation onerel, VacuumParams *params,
 		}
 
 		/*
+		 * Should we build extended statistics for this relation?
+		 *
+		 * The extended statistics catalog does not include an inheritance
+		 * flag, so we can't store statistics built both with and without
+		 * data from child relations. We can store just one set of statistics
+		 * per relation. For plain relations that's fine, but for inheritance
+		 * trees we have to pick whether to store statistics for just the
+		 * one relation or the whole tree. For plain inheritance we store
+		 * the (!inh) version, mostly for backwards compatibility reasons.
+		 * For partitioned tables that's pointless (the non-leaf tables are
+		 * always empty), so we store stats representing the whole tree.
+		 */
+		build_ext_stats = (onerel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE) ? inh : (!inh);
+
+		/*
 		 * Build extended statistics (if there are any).
 		 *
 		 * For now we only build extended statistics on individual relations,
 		 * not for relations representing inheritance trees.
 		 */
-		if (!inh)
+		if (build_ext_stats)
 			BuildRelationExtStatistics(onerel, totalrows, numrows, rows,
 									   attr_cnt, vacattrstats);
 	}
diff --git a/src/backend/statistics/dependencies.c b/src/backend/statistics/dependencies.c
index f1602cd3a26..bbc29b67117 100644
--- a/src/backend/statistics/dependencies.c
+++ b/src/backend/statistics/dependencies.c
@@ -1418,10 +1418,13 @@ dependencies_clauselist_selectivity(PlannerInfo *root,
 	int			unique_exprs_cnt;
 
 	/*
-	 * When dealing with inheritance trees, ignore extended stats (which were
-	 * built without data from child rels, and thus do not represent them).
+	 * When dealing with regular inheritance trees, ignore extended stats
+	 * (which were built without data from child rels, and thus do not
+	 * represent them). For partitioned tables data there's no data in the
+	 * non-leaf relations, so we build stats only for the inheritance tree.
+	 * So for partitioned tables we do consider extended stats.
 	 */
-	if (rte->inh)
+	if (rte->inh && rte->relkind != RELKIND_PARTITIONED_TABLE)
 		return 1.0;
 
 	/* check if there's any stats that might be useful for us. */
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index b23c15e9db4..5762621673b 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -1698,10 +1698,13 @@ statext_mcv_clauselist_selectivity(PlannerInfo *root, List *clauses, int varReli
 	RangeTblEntry *rte = planner_rt_fetch(rel->relid, root);
 
 	/*
-	 * When dealing with inheritance trees, ignore extended stats (which were
-	 * built without data from child rels, and thus do not represent them).
+	 * When dealing with regular inheritance trees, ignore extended stats
+	 * (which were built without data from child rels, and thus do not
+	 * represent them). For partitioned tables data there's no data in the
+	 * non-leaf relations, so we build stats only for the inheritance tree.
+	 * So for partitioned tables we do consider extended stats.
 	 */
-	if (rte->inh)
+	if (rte->inh && rte->relkind != RELKIND_PARTITIONED_TABLE)
 		return sel;
 
 	/* check if there's any stats that might be useful for us. */
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 9e39f9888e1..5d56748f0a7 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -3913,19 +3913,23 @@ estimate_multivariate_ndistinct(PlannerInfo *root, RelOptInfo *rel,
 	Oid			statOid = InvalidOid;
 	MVNDistinct *stats;
 	StatisticExtInfo *matched_info = NULL;
-	RangeTblEntry		*rte = planner_rt_fetch(rel->relid, root);
-
-	/*
-	 * When dealing with inheritance trees, ignore extended stats (which were
-	 * built without data from child rels, and thus do not represent them).
-	 */
-	if (rte->inh)
-		return false;
+	RangeTblEntry		*rte;
 
 	/* bail out immediately if the table has no extended statistics */
 	if (!rel->statlist)
 		return false;
 
+	/*
+	 * When dealing with regular inheritance trees, ignore extended stats
+	 * (which were built without data from child rels, and thus do not
+	 * represent them). For partitioned tables data there's no data in the
+	 * non-leaf relations, so we build stats only for the inheritance tree.
+	 * So for partitioned tables we do consider extended stats.
+	 */
+	rte = planner_rt_fetch(rel->relid, root);
+	if (rte->inh && rte->relkind != RELKIND_PARTITIONED_TABLE)
+		return false;
+
 	/* look for the ndistinct statistics object matching the most vars */
 	nmatches_vars = 0;			/* we require at least two matches */
 	nmatches_exprs = 0;
@@ -5242,11 +5246,14 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
 				break;
 
 			/*
-			 * When dealing with inheritance trees, ignore extended stats (which
-			 * were built without data from child rels, and so do not represent
-			 * them).
+			 * When dealing with regular inheritance trees, ignore extended
+			 * stats (which were built without data from child rels, and thus
+			 * do not represent them). For partitioned tables data there's no
+			 * data in the non-leaf relations, so we build stats only for the
+			 * inheritance tree. So for partitioned tables we do consider
+			 * extended stats.
 			 */
-			if (rte->inh)
+			if (rte->inh && rte->relkind != RELKIND_PARTITIONED_TABLE)
 				break;
 
 			/* skip stats without per-expression stats */