pg_test_fsync — determine fastest wal_sync_method for PostgreSQL
pg_test_fsync [option...]
pg_test_fsync is intended to give you a reasonable
idea of what the fastest wal_sync_method is on your
specific system,
as well as supplying diagnostic information in the event of an identified I/O
problem. However, differences shown by
pg_test_fsync might not make any significant
difference in real database throughput, especially since many database servers
are not speed-limited by their write-ahead logs.
pg_test_fsync reports average file sync operation
time in microseconds for each wal_sync_method, which can also be used to
inform efforts to optimize the value of commit_delay.
pg_test_fsync accepts the following command-line options:
-f--filename
Specifies the file name to write test data in.
This file should be in the same file system that the
pg_wal directory is or will be placed in.
(pg_wal contains the WAL files.)
The default is pg_test_fsync.out in the current
directory.
-s--secs-per-testSpecifies the number of seconds for each test. The more time per test, the greater the test's accuracy, but the longer it takes to run. The default is 5 seconds, which allows the program to complete in under 2 minutes.
-V--versionPrint the pg_test_fsync version and exit.
-?--helpShow help about pg_test_fsync command line arguments, and exit.
The environment variable PG_COLOR specifies whether to use
color in diagnostic messages. Possible values are
always, auto and
never.