In pg_dump, don't dump a stats object unless dumping underlying table.

If the underlying table isn't being dumped, it's useless to dump
an extended statistics object; it'll just cause errors at restore.
We have always applied similar policies to, say, indexes.

(When and if we get cross-table stats objects, it might be profitable
to think a little harder about what to do with them.  But for now
there seems no point in considering a stats object as anything but
an appendage of its table.)

Rian McGuire and Tom Lane, per report from Rian McGuire.
Back-patch to supported branches.

Discussion: https://postgr.es/m/7075d3aa-3f05-44a5-b68f-47dc6a8a0550@buildkite.com

src/bin/pg_dump/pg_dump.c

@@ -1815,6 +1815,26 @@ selectDumpablePublicationTable(DumpableObject *dobj, Archive *fout)
 		DUMP_COMPONENT_ALL : DUMP_COMPONENT_NONE;
 }
 
+/*
+ * selectDumpableStatisticsObject: policy-setting subroutine
+ *		Mark an extended statistics object as to be dumped or not
+ *
+ * We dump an extended statistics object if the schema it's in and the table
+ * it's for are being dumped.  (This'll need more thought if statistics
+ * objects ever support cross-table stats.)
+ */
+static void
+selectDumpableStatisticsObject(StatsExtInfo *sobj, Archive *fout)
+{
+	if (checkExtensionMembership(&sobj->dobj, fout))
+		return;					/* extension membership overrides all else */
+
+	sobj->dobj.dump = sobj->dobj.namespace->dobj.dump_contains;
+	if (sobj->stattable == NULL ||
+		!(sobj->stattable->dobj.dump & DUMP_COMPONENT_DEFINITION))
+		sobj->dobj.dump = DUMP_COMPONENT_NONE;
+}
+
 /*
  * selectDumpableObject: policy-setting subroutine
  *		Mark a generic dumpable object as to be dumped or not
@@ -7492,6 +7512,7 @@ getExtendedStatistics(Archive *fout)
 	int			i_stxname;
 	int			i_stxnamespace;
 	int			i_rolname;
+	int			i_stxrelid;
 	int			i_stattarget;
 	int			i;
 
@@ -7503,12 +7524,12 @@ getExtendedStatistics(Archive *fout)
 
 	if (fout->remoteVersion < 130000)
 		appendPQExpBuffer(query, "SELECT tableoid, oid, stxname, "
-						  "stxnamespace, (%s stxowner) AS rolname, (-1) AS stxstattarget "
+						  "stxnamespace, (%s stxowner) AS rolname, stxrelid, (-1) AS stxstattarget "
 						  "FROM pg_catalog.pg_statistic_ext",
 						  username_subquery);
 	else
 		appendPQExpBuffer(query, "SELECT tableoid, oid, stxname, "
-						  "stxnamespace, (%s stxowner) AS rolname, stxstattarget "
+						  "stxnamespace, (%s stxowner) AS rolname, stxrelid, stxstattarget "
 						  "FROM pg_catalog.pg_statistic_ext",
 						  username_subquery);
 
@@ -7521,6 +7542,7 @@ getExtendedStatistics(Archive *fout)
 	i_stxname = PQfnumber(res, "stxname");
 	i_stxnamespace = PQfnumber(res, "stxnamespace");
 	i_rolname = PQfnumber(res, "rolname");
+	i_stxrelid = PQfnumber(res, "stxrelid");
 	i_stattarget = PQfnumber(res, "stxstattarget");
 
 	statsextinfo = (StatsExtInfo *) pg_malloc(ntups * sizeof(StatsExtInfo));
@@ -7536,10 +7558,12 @@ getExtendedStatistics(Archive *fout)
 			findNamespace(fout,
 						  atooid(PQgetvalue(res, i, i_stxnamespace)));
 		statsextinfo[i].rolname = pg_strdup(PQgetvalue(res, i, i_rolname));
+		statsextinfo[i].stattable =
+			findTableByOid(atooid(PQgetvalue(res, i, i_stxrelid)));
 		statsextinfo[i].stattarget = atoi(PQgetvalue(res, i, i_stattarget));
 
 		/* Decide whether we want to dump it */
-		selectDumpableObject(&(statsextinfo[i].dobj), fout);
+		selectDumpableStatisticsObject(&(statsextinfo[i]), fout);
 
 		/* Stats objects do not currently have ACLs. */
 		statsextinfo[i].dobj.dump &= ~DUMP_COMPONENT_ACL;

src/bin/pg_dump/pg_dump.h

@@ -387,6 +387,7 @@ typedef struct _statsExtInfo
 {
 	DumpableObject dobj;
 	char	   *rolname;		/* name of owner, or empty string */
+	TableInfo  *stattable;		/* link to table the stats are for */
 	int			stattarget;		/* statistics target */
 } StatsExtInfo;
 

src/bin/pg_dump/t/002_pg_dump.pl

@@ -2751,13 +2751,13 @@ my %tests = (
 	'CREATE STATISTICS extended_stats_no_options' => {
 		create_order => 97,
 		create_sql   => 'CREATE STATISTICS dump_test.test_ext_stats_no_options
-							ON col1, col2 FROM dump_test.test_fifth_table',
+							ON col1, col2 FROM dump_test.test_table',
 		regexp => qr/^
-			\QCREATE STATISTICS dump_test.test_ext_stats_no_options ON col1, col2 FROM dump_test.test_fifth_table;\E
+			\QCREATE STATISTICS dump_test.test_ext_stats_no_options ON col1, col2 FROM dump_test.test_table;\E
 		    /xms,
 		like =>
 		  { %full_runs, %dump_test_schema_runs, section_post_data => 1, },
-		unlike => { exclude_dump_test_schema => 1, },
+		unlike => { exclude_dump_test_schema => 1, exclude_test_table => 1, },
 	},
 
 	'CREATE STATISTICS extended_stats_options' => {