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pg_stat_reset_slru()
A function for resetting SLRU statistics
pg_stat_reset_slru() is a system function for resetting SLRU cache statistics as displayed by the pg_stat_slru view.
pg_stat_reset_slru() was added in PostgreSQL 13.
Usage
pg_stat_reset_slru ( text ) → void
If the provided argument is NULL, all SLRU cache statistics are reset.
Individual statistics can be reset by providing one of the following (case-sensitive) values as the argument:
CommitTsMultiXactMemberMultiXactOffsetNotifySerialSubtransXact
No kind of error or warning will be raised if an invalid value is provided.
Change history
- PostgreSQL 13
- added (commit 28cac71b)
Examples
Given SLRU statistics in the following state:
postgres=# SELECT * FROM pg_stat_slru;
name | blks_zeroed | blks_hit | blks_read | blks_written | blks_exists | flushes | truncates | stats_reset
-----------------+-------------+----------+-----------+--------------+-------------+---------+-----------+-------------------------------
CommitTs | 1 | 95 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
MultiXactMember | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
MultiXactOffset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
Notify | 1 | 5 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
Serial | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
Subtrans | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
Xact | 0 | 1131 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
other | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
(8 rows)
the statistics for a single SLRU cache can be reset with e.g.:
postgres=# SELECT pg_stat_reset_slru('Notify');
pg_stat_reset_slru
--------------------
(1 row)
Time: 5.560 ms
postgres=# SELECT * FROM pg_stat_slru;
name | blks_zeroed | blks_hit | blks_read | blks_written | blks_exists | flushes | truncates | stats_reset
-----------------+-------------+----------+-----------+--------------+-------------+---------+-----------+-------------------------------
CommitTs | 1 | 95 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
MultiXactMember | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
MultiXactOffset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
Notify | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-22 01:17:05.79368+01
Serial | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
Subtrans | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
Xact | 0 | 1131 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
other | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-03 11:08:05.213091+01
(8 rows)
Resetting statistics for all caches:
postgres=# SELECT pg_stat_reset_slru(NULL);
pg_stat_reset_slru
--------------------
(1 row)
postgres=# SELECT * FROM pg_stat_slru;
name | blks_zeroed | blks_hit | blks_read | blks_written | blks_exists | flushes | truncates | stats_reset
-----------------+-------------+----------+-----------+--------------+-------------+---------+-----------+-------------------------------
CommitTs | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-22 01:18:05.565189+01
MultiXactMember | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-22 01:18:05.565189+01
MultiXactOffset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-22 01:18:05.565189+01
Notify | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-22 01:18:05.565189+01
Serial | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-22 01:18:05.565189+01
Subtrans | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-22 01:18:05.565189+01
Xact | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-22 01:18:05.565189+01
other | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2021-11-22 01:18:05.565189+01
(8 rows)
Providing the name of a non-existent SLRU cache:
postgres=# SELECT pg_stat_reset_slru('foo');
pg_stat_reset_slru
--------------------
(1 row)
References
- PostgreSQL documentation: Additional Statistics Functions
