track_wal_io_timing
A parameter determining whether to track timing of WAL I/O
This entry relates to a PostgreSQL feature which is part of PostgreSQL 14, due to be released in late 2021.
track_wal_io_timing is a configuration parameter timing of WAL I/O calls.
track_wal_io_timing was added in PostgreSQL 14.
Default value
The default value for track_wal_io_timing is: off.
Usage
If set to on, track_wal_io_timing will track statistics for WAL input/output operations. The accumulated statistics can be retrieved via the following columns of pg_stat_wal:
wal_write_timewal_sync_time
Note that if enabled, track_wal_io_timing will cause PostgreSQL to query the operating system for the current time whenever WAL is written or synced, which may cause significant overhead on some platforms.
Change history
- PostgreSQL 14
- added (commit ff99918c)
Examples
Sample contents of pg_stat_wal with track_wal_io_timing set to on:
postgres=# SELECT * FROM pg_stat_wal\gx -[ RECORD 1 ]----+------------------------------ wal_records | 301882 wal_fpi | 135 wal_bytes | 18544842 wal_buffers_full | 603 wal_write | 633 wal_sync | 5 wal_write_time | 4.13 wal_sync_time | 219.9 stats_reset | 2021-03-09 11:06:01.842869+01
References
- PostgreSQL documentation: track_wal_io_timing