vacuumdb: Do not run VACUUM (ONLY_DATABASE_STATS) when --analyze-only.

Previously, vacuumdb --analyze-only issued VACUUM (ONLY_DATABASE_STATS)
at the end. Since --analyze-only is meant to update optimizer statistics only,
this extra VACUUM command is unnecessary.

This commit prevents vacuumdb --analyze-only from running that redundant
VACUUM command.

Author: Fujii Masao <masao.fujii@gmail.com>
Reviewed-by: Mircea Cadariu <cadariu.mircea@gmail.com>
Discussion: https://postgr.es/m/CAHGQGwEqHGa-k=wbRMucUVihHVXk4NQkK94GNN=ym9cQ5HBSHg@mail.gmail.com

src/bin/scripts/t/100_vacuumdb.pl

@@ -351,5 +351,11 @@ $node->issues_sql_like(
 	],
 	qr/statement: ANALYZE public.parent_table/s,
 	'--analyze-only updates statistics for partitioned tables');
+$node->issues_sql_unlike(
+	[
+		'vacuumdb', '--analyze-only', 'postgres'
+	],
+	qr/statement:\ VACUUM/sx,
+	'--analyze-only does not run vacuum');
 
 done_testing();

src/bin/scripts/vacuumdb.c

@@ -750,7 +750,8 @@ vacuum_one_database(ConnParams *cparams,
 	}
 
 	/* If we used SKIP_DATABASE_STATS, mop up with ONLY_DATABASE_STATS */
-	if (vacopts->skip_database_stats && stage == ANALYZE_NO_STAGE)
+	if (vacopts->skip_database_stats && stage == ANALYZE_NO_STAGE &&
+		!vacopts->analyze_only)
 	{
 		const char *cmd = "VACUUM (ONLY_DATABASE_STATS);";
 		ParallelSlot *free_slot = ParallelSlotsGetIdle(sa, NULL);