Add ability to reset all shared stats types in pg_stat_reset_shared()

Currently, pg_stat_reset_shared() can use an argument to specify the
target of statistics to reset, doing nothing for NULL as it is strict.

This patch adds to pg_stat_reset_shared() the possibility to reset all
the stats types already handled in this function rather than do nothing
if the argument value given is NULL or if nothing is specified
(proisstrict is switched to false).  Like previously, SLRUs are not
included in what gets reset.

The idea to use NULL or no argument to control if all the shared stats
already covered by this function should be reset has been proposed by
Andres Freund.

Bump catalog version.

Author: Atsushi Torikoshi
Reviewed-by: Kyotaro Horiguchi, Michael Paquier, Bharath Rupireddy,
Matthias van de Meent
Discussion: https://postgr.es/m/4291a55137ddda77cf7cc5f46e846daf@oss.nttdata.com

doc/src/sgml/monitoring.sgml

@@ -4712,7 +4712,7 @@ description | Waiting for a newly initialized WAL file to reach durable storage
         <indexterm>
          <primary>pg_stat_reset_shared</primary>
         </indexterm>
-        <function>pg_stat_reset_shared</function> ( <type>text</type> )
+        <function>pg_stat_reset_shared</function> ( [ <parameter>target</parameter> <type>text</type> <literal>DEFAULT</literal> <literal>NULL</literal> ] )
         <returnvalue>void</returnvalue>
        </para>
        <para>
@@ -4730,6 +4730,9 @@ description | Waiting for a newly initialized WAL file to reach durable storage
         <structname>pg_stat_wal</structname> view or
         <literal>recovery_prefetch</literal> to reset all the counters shown
         in the <structname>pg_stat_recovery_prefetch</structname> view.
+        If <parameter>target</parameter> is <literal>NULL</literal> or
+        is not specified, all the counters from the views listed above are
+        reset.
        </para>
        <para>
         This function is restricted to superusers by default, but other users

src/backend/catalog/system_functions.sql

@@ -621,6 +621,13 @@ LANGUAGE internal
 STRICT IMMUTABLE PARALLEL SAFE
 AS 'unicode_is_normalized';
 
+CREATE OR REPLACE FUNCTION
+  pg_stat_reset_shared(target text DEFAULT NULL)
+RETURNS void
+LANGUAGE INTERNAL
+CALLED ON NULL INPUT VOLATILE PARALLEL SAFE
+AS 'pg_stat_reset_shared';
+
 --
 -- The default permissions for functions mean that anyone can execute them.
 -- A number of functions shouldn't be executable by just anyone, but rather

src/backend/utils/adt/pgstatfuncs.c

@@ -1685,7 +1685,22 @@ pg_stat_reset(PG_FUNCTION_ARGS)
 Datum
 pg_stat_reset_shared(PG_FUNCTION_ARGS)
 {
-	char	   *target = text_to_cstring(PG_GETARG_TEXT_PP(0));
+	char	   *target = NULL;
+
+	if (PG_ARGISNULL(0))
+	{
+		/* Reset all the statistics when nothing is specified */
+		pgstat_reset_of_kind(PGSTAT_KIND_ARCHIVER);
+		pgstat_reset_of_kind(PGSTAT_KIND_BGWRITER);
+		pgstat_reset_of_kind(PGSTAT_KIND_CHECKPOINTER);
+		pgstat_reset_of_kind(PGSTAT_KIND_IO);
+		XLogPrefetchResetStats();
+		pgstat_reset_of_kind(PGSTAT_KIND_WAL);
+
+		PG_RETURN_VOID();
+	}
+
+	target = text_to_cstring(PG_GETARG_TEXT_PP(0));
 
 	if (strcmp(target, "archiver") == 0)
 		pgstat_reset_of_kind(PGSTAT_KIND_ARCHIVER);

src/include/catalog/catversion.h

@@ -57,6 +57,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	202310301
+#define CATALOG_VERSION_NO	202311121
 
 #endif

src/include/catalog/pg_proc.dat

@@ -5881,8 +5881,9 @@
   prorettype => 'void', proargtypes => '', prosrc => 'pg_stat_reset' },
 { oid => '3775',
   descr => 'statistics: reset collected statistics shared across the cluster',
-  proname => 'pg_stat_reset_shared', provolatile => 'v', prorettype => 'void',
-  proargtypes => 'text', prosrc => 'pg_stat_reset_shared' },
+  proname => 'pg_stat_reset_shared', proisstrict => 'f', provolatile => 'v',
+  prorettype => 'void', proargtypes => 'text',
+  prosrc => 'pg_stat_reset_shared' },
 { oid => '3776',
   descr => 'statistics: reset collected statistics for a single table or index in the current database or shared across all databases in the cluster',
   proname => 'pg_stat_reset_single_table_counters', provolatile => 'v',

src/test/regress/expected/stats.out

@@ -975,38 +975,39 @@ SELECT stats_reset > :'wal_reset_ts'::timestamptz FROM pg_stat_wal;
 (1 row)
 
 SELECT stats_reset AS wal_reset_ts FROM pg_stat_wal \gset
--- Test that reset_shared with no specified stats type doesn't reset anything
-SELECT pg_stat_reset_shared(NULL);
+-- Test that reset_shared with no argument resets all the stats types
+-- supported (providing NULL as argument has the same effect).
+SELECT pg_stat_reset_shared();
  pg_stat_reset_shared 
 ----------------------
  
 (1 row)
 
-SELECT stats_reset = :'archiver_reset_ts'::timestamptz FROM pg_stat_archiver;
+SELECT stats_reset > :'archiver_reset_ts'::timestamptz FROM pg_stat_archiver;
  ?column? 
 ----------
  t
 (1 row)
 
-SELECT stats_reset = :'bgwriter_reset_ts'::timestamptz FROM pg_stat_bgwriter;
+SELECT stats_reset > :'bgwriter_reset_ts'::timestamptz FROM pg_stat_bgwriter;
  ?column? 
 ----------
  t
 (1 row)
 
-SELECT stats_reset = :'checkpointer_reset_ts'::timestamptz FROM pg_stat_checkpointer;
+SELECT stats_reset > :'checkpointer_reset_ts'::timestamptz FROM pg_stat_checkpointer;
  ?column? 
 ----------
  t
 (1 row)
 
-SELECT stats_reset = :'recovery_prefetch_reset_ts'::timestamptz FROM pg_stat_recovery_prefetch;
+SELECT stats_reset > :'recovery_prefetch_reset_ts'::timestamptz FROM pg_stat_recovery_prefetch;
  ?column? 
 ----------
  t
 (1 row)
 
-SELECT stats_reset = :'wal_reset_ts'::timestamptz FROM pg_stat_wal;
+SELECT stats_reset > :'wal_reset_ts'::timestamptz FROM pg_stat_wal;
  ?column? 
 ----------
  t

src/test/regress/sql/stats.sql

@@ -488,13 +488,14 @@ SELECT pg_stat_reset_shared('wal');
 SELECT stats_reset > :'wal_reset_ts'::timestamptz FROM pg_stat_wal;
 SELECT stats_reset AS wal_reset_ts FROM pg_stat_wal \gset
 
--- Test that reset_shared with no specified stats type doesn't reset anything
-SELECT pg_stat_reset_shared(NULL);
-SELECT stats_reset = :'archiver_reset_ts'::timestamptz FROM pg_stat_archiver;
-SELECT stats_reset = :'bgwriter_reset_ts'::timestamptz FROM pg_stat_bgwriter;
-SELECT stats_reset = :'checkpointer_reset_ts'::timestamptz FROM pg_stat_checkpointer;
-SELECT stats_reset = :'recovery_prefetch_reset_ts'::timestamptz FROM pg_stat_recovery_prefetch;
-SELECT stats_reset = :'wal_reset_ts'::timestamptz FROM pg_stat_wal;
+-- Test that reset_shared with no argument resets all the stats types
+-- supported (providing NULL as argument has the same effect).
+SELECT pg_stat_reset_shared();
+SELECT stats_reset > :'archiver_reset_ts'::timestamptz FROM pg_stat_archiver;
+SELECT stats_reset > :'bgwriter_reset_ts'::timestamptz FROM pg_stat_bgwriter;
+SELECT stats_reset > :'checkpointer_reset_ts'::timestamptz FROM pg_stat_checkpointer;
+SELECT stats_reset > :'recovery_prefetch_reset_ts'::timestamptz FROM pg_stat_recovery_prefetch;
+SELECT stats_reset > :'wal_reset_ts'::timestamptz FROM pg_stat_wal;
 
 -- Test error case for reset_shared with unknown stats type
 SELECT pg_stat_reset_shared('unknown');