Add target "slru" to pg_stat_reset_shared()

Currently, pg_stat_reset_shared() cannot reset the counters in the view
pg_stat_slru even if it is a type of shared stats.  This patch adds
support for a new value in pg_stat_reset_shared(), called "slru", able
to do that.  Note that pg_stat_reset_shared(NULL) also resets SLRU
counters.

There may be a point in removing pg_stat_reset_slru() that was
introduced in 28cac71bd368 (v13~) as the new option overlaps with this
function, but we would lose the ability to reset individual SLRU
counters.  This is left for future reconsideration.

Author: Atsushi Torikoshi
Discussion: https://postgr.es/m/e3c25d72e81378e7b64f3c52e0306fc9@oss.nttdata.com

2 files changed, 29 insertions, 1 deletions

diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 6ed3584a763..7869c598f92 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -960,6 +960,21 @@ SELECT stats_reset > :'recovery_prefetch_reset_ts'::timestamptz FROM pg_stat_rec
 (1 row)
 
 SELECT stats_reset AS recovery_prefetch_reset_ts FROM pg_stat_recovery_prefetch \gset
+-- Test that reset_shared with slru specified as the stats type works
+SELECT max(stats_reset) AS slru_reset_ts FROM pg_stat_slru \gset
+SELECT pg_stat_reset_shared('slru');
+ pg_stat_reset_shared 
+----------------------
+ 
+(1 row)
+
+SELECT max(stats_reset) > :'slru_reset_ts'::timestamptz FROM pg_stat_slru;
+ ?column? 
+----------
+ t
+(1 row)
+
+SELECT max(stats_reset) AS slru_reset_ts FROM pg_stat_slru \gset
 -- Test that reset_shared with wal specified as the stats type works
 SELECT stats_reset AS wal_reset_ts FROM pg_stat_wal \gset
 SELECT pg_stat_reset_shared('wal');
@@ -1007,6 +1022,12 @@ SELECT stats_reset > :'recovery_prefetch_reset_ts'::timestamptz FROM pg_stat_rec
  t
 (1 row)
 
+SELECT max(stats_reset) > :'slru_reset_ts'::timestamptz FROM pg_stat_slru;
+ ?column? 
+----------
+ t
+(1 row)
+
 SELECT stats_reset > :'wal_reset_ts'::timestamptz FROM pg_stat_wal;
  ?column? 
 ----------
@@ -1016,7 +1037,7 @@ 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');
 ERROR:  unrecognized reset target: "unknown"
-HINT:  Target must be "archiver", "bgwriter", "checkpointer", "io", "recovery_prefetch", or "wal".
+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();
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index fd8afeeae51..5b4e451a2e3 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -482,6 +482,12 @@ SELECT pg_stat_reset_shared('recovery_prefetch');
 SELECT stats_reset > :'recovery_prefetch_reset_ts'::timestamptz FROM pg_stat_recovery_prefetch;
 SELECT stats_reset AS recovery_prefetch_reset_ts FROM pg_stat_recovery_prefetch \gset
 
+-- Test that reset_shared with slru specified as the stats type works
+SELECT max(stats_reset) AS slru_reset_ts FROM pg_stat_slru \gset
+SELECT pg_stat_reset_shared('slru');
+SELECT max(stats_reset) > :'slru_reset_ts'::timestamptz FROM pg_stat_slru;
+SELECT max(stats_reset) AS slru_reset_ts FROM pg_stat_slru \gset
+
 -- Test that reset_shared with wal specified as the stats type works
 SELECT stats_reset AS wal_reset_ts FROM pg_stat_wal \gset
 SELECT pg_stat_reset_shared('wal');
@@ -495,6 +501,7 @@ 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 max(stats_reset) > :'slru_reset_ts'::timestamptz FROM pg_stat_slru;
 SELECT stats_reset > :'wal_reset_ts'::timestamptz FROM pg_stat_wal;
 
 -- Test error case for reset_shared with unknown stats type