pg_test_fsync — determine fastest
wal_sync_method for PostgreSQL
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:
Specifies the file name to write test data in. This file should be in the same file system that the
pg_waldirectory is or will be placed in. (
pg_walcontains the WAL files.) The default is
pg_test_fsync.outin the current directory.
Specifies 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.
Print the pg_test_fsync version and exit.
Show 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