Add pg_stat_wal statistics view.

This view shows the statistics about WAL activity. Currently it has only
two columns: wal_buffers_full and stats_reset. wal_buffers_full column
indicates the number of times WAL data was written to the disk because
WAL buffers got full. This information is useful when tuning wal_buffers.
stats_reset column indicates the time at which these statistics were
last reset.

pg_stat_wal view is also the basic infrastructure to expose other
various statistics about WAL activity later.

Bump PGSTAT_FILE_FORMAT_ID due to the change in pgstat format.

Bump catalog version.

Author: Masahiro Ikeda
Reviewed-by: Takayuki Tsunakawa, Kyotaro Horiguchi, Amit Kapila, Fujii Masao
Discussion: https://postgr.es/m/[email protected]

3 files changed, 13 insertions, 0 deletions

diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 2a18dc423e2..af4192f9a87 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -2129,6 +2129,9 @@ pg_stat_user_tables| SELECT pg_stat_all_tables.relid,
     pg_stat_all_tables.autoanalyze_count
    FROM pg_stat_all_tables
   WHERE ((pg_stat_all_tables.schemaname <> ALL (ARRAY['pg_catalog'::name, 'information_schema'::name])) AND (pg_stat_all_tables.schemaname !~ '^pg_toast'::text));
+pg_stat_wal| SELECT w.wal_buffers_full,
+    w.stats_reset
+   FROM pg_stat_get_wal() w(wal_buffers_full, stats_reset);
 pg_stat_wal_receiver| SELECT s.pid,
     s.status,
     s.receive_start_lsn,
diff --git a/src/test/regress/expected/sysviews.out b/src/test/regress/expected/sysviews.out
index 1cffc3349d6..81bdacf59da 100644
--- a/src/test/regress/expected/sysviews.out
+++ b/src/test/regress/expected/sysviews.out
@@ -76,6 +76,13 @@ select count(*) >= 0 as ok from pg_prepared_xacts;
  t
 (1 row)
 
+-- There must be only one record
+select count(*) = 1 as ok from pg_stat_wal;
+ ok 
+----
+ t
+(1 row)
+
 -- This is to record the prevailing planner enable_foo settings during
 -- a regression test run.
 select name, setting from pg_settings where name like 'enable%';
diff --git a/src/test/regress/sql/sysviews.sql b/src/test/regress/sql/sysviews.sql
index ac4a0e1cbba..b9b875bc6ab 100644
--- a/src/test/regress/sql/sysviews.sql
+++ b/src/test/regress/sql/sysviews.sql
@@ -37,6 +37,9 @@ select count(*) = 0 as ok from pg_prepared_statements;
 -- See also prepared_xacts.sql
 select count(*) >= 0 as ok from pg_prepared_xacts;
 
+-- There must be only one record
+select count(*) = 1 as ok from pg_stat_wal;
+
 -- This is to record the prevailing planner enable_foo settings during
 -- a regression test run.
 select name, setting from pg_settings where name like 'enable%';