Make pg_stat_reset() return the reset time

Author: shinyaaa

doc/src/sgml/monitoring.sgml

@@ -5068,10 +5068,11 @@ description | Waiting for a newly initialized WAL file to reach durable storage
          <primary>pg_stat_reset</primary>
         </indexterm>
         <function>pg_stat_reset</function> ()
-        <returnvalue>void</returnvalue>
+        <returnvalue>timestamp with time zone</returnvalue>
        </para>
        <para>
-        Resets all statistics counters for the current database to zero.
+        Resets all statistics counters for the current database to zero, and
+        returns the time of the reset.
        </para>
        <para>
         This function is restricted to superusers by default, but other users

src/backend/utils/activity/pgstat.c

@@ -832,14 +832,16 @@ match_db_entries(PgStatShared_HashEntry *entry, Datum match_data)
  * Permission checking for this function is managed through the normal
  * GRANT system.
  */
-void
+TimestampTz
 pgstat_reset_counters(void)
 {
 	TimestampTz ts = GetCurrentTimestamp();
 
 	pgstat_reset_matching_entries(match_db_entries,
 								  ObjectIdGetDatum(MyDatabaseId),
 								  ts);
+
+	return ts;
 }
 
 /*

src/backend/utils/adt/pgstatfuncs.c

@@ -1878,9 +1878,9 @@ pg_stat_force_next_flush(PG_FUNCTION_ARGS)
 Datum
 pg_stat_reset(PG_FUNCTION_ARGS)
 {
-	pgstat_reset_counters();
+	TimestampTz ts = pgstat_reset_counters();
 
-	PG_RETURN_VOID();
+	PG_RETURN_TIMESTAMPTZ(ts);
 }
 
 /*

src/include/catalog/pg_proc.dat

@@ -6160,7 +6160,7 @@
 { oid => '2274',
   descr => 'statistics: reset collected statistics for current database',
   proname => 'pg_stat_reset', proisstrict => 'f', provolatile => 'v',
-  prorettype => 'void', proargtypes => '', prosrc => 'pg_stat_reset' },
+  prorettype => 'timestamptz', proargtypes => '', prosrc => 'pg_stat_reset' },
 { oid => '3775',
   descr => 'statistics: reset collected statistics shared across the cluster',
   proname => 'pg_stat_reset_shared', proisstrict => 'f', provolatile => 'v',

src/include/pgstat.h

@@ -529,7 +529,7 @@ extern void pgstat_initialize(void);
 extern long pgstat_report_stat(bool force);
 extern void pgstat_force_next_flush(void);
 
-extern void pgstat_reset_counters(void);
+extern TimestampTz pgstat_reset_counters(void);
 extern void pgstat_reset(PgStat_Kind kind, Oid dboid, uint64 objid);
 extern void pgstat_reset_of_kind(PgStat_Kind kind);
 

src/test/isolation/expected/stats.out

@@ -1313,10 +1313,10 @@ name          |pg_stat_get_function_calls|total_above_zero|self_above_zero
 test_stat_func|                         2|t               |t              
 (1 row)
 
-step s1_reset: SELECT pg_stat_reset();
-pg_stat_reset
--------------
-             
+step s1_reset: SELECT pg_stat_reset() IS NOT NULL AS t;
+t
+-
+t
 (1 row)
 
 step s1_func_stats: 

src/test/isolation/expected/stats_1.out

@@ -1313,10 +1313,10 @@ name          |pg_stat_get_function_calls|total_above_zero|self_above_zero
 test_stat_func|                         2|t               |t              
 (1 row)
 
-step s1_reset: SELECT pg_stat_reset();
-pg_stat_reset
--------------
-             
+step s1_reset: SELECT pg_stat_reset() IS NOT NULL AS t;
+t
+-
+t
 (1 row)
 
 step s1_func_stats: 

src/test/isolation/specs/stats.spec

@@ -63,7 +63,7 @@ step s1_func_stats_reset_check {
         IS NOT NULL AS has_stats_reset;
 }
 step s1_func_stats_reset_nonexistent { SELECT pg_stat_reset_single_function_counters(12000); }
-step s1_reset { SELECT pg_stat_reset(); }
+step s1_reset { SELECT pg_stat_reset() IS NOT NULL AS t; }
 step s1_func_stats {
     SELECT
         tso.name,

src/test/regress/expected/stats.out

@@ -1133,17 +1133,17 @@ ERROR:  unrecognized reset target: "unknown"
 HINT:  Target must be "archiver", "bgwriter", "checkpointer", "io", "recovery_prefetch", "slru", or "wal".
 -- Test that reset works for pg_stat_database
 -- Since pg_stat_database stats_reset starts out as NULL, reset it once first so we have something to compare it to
-SELECT pg_stat_reset();
- pg_stat_reset 
----------------
- 
+SELECT pg_stat_reset() IS NOT NULL AS t;
+ t 
+---
+ t
 (1 row)
 
 SELECT stats_reset AS db_reset_ts FROM pg_stat_database WHERE datname = (SELECT current_database()) \gset
-SELECT pg_stat_reset();
- pg_stat_reset 
----------------
- 
+SELECT pg_stat_reset() IS NOT NULL AS t;
+ t 
+---
+ t
 (1 row)
 
 SELECT stats_reset > :'db_reset_ts'::timestamptz FROM pg_stat_database WHERE datname = (SELECT current_database());

src/test/regress/sql/stats.sql

@@ -526,9 +526,9 @@ SELECT pg_stat_reset_shared('unknown');
 -- Test that reset works for pg_stat_database
 
 -- Since pg_stat_database stats_reset starts out as NULL, reset it once first so we have something to compare it to
-SELECT pg_stat_reset();
+SELECT pg_stat_reset() IS NOT NULL AS t;
 SELECT stats_reset AS db_reset_ts FROM pg_stat_database WHERE datname = (SELECT current_database()) \gset
-SELECT pg_stat_reset();
+SELECT pg_stat_reset() IS NOT NULL AS t;
 SELECT stats_reset > :'db_reset_ts'::timestamptz FROM pg_stat_database WHERE datname = (SELECT current_database());