NAME

       pg_test_fsync - determine fastest wal_sync_method for PostgreSQL

SYNOPSIS

       pg_test_fsync [option...]

DESCRIPTION

       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.

OPTIONS

       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-test
           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.

       -V
       --version
           Print the pg_test_fsync version and exit.

       -?
       --help
           Show help about pg_test_fsync command line arguments, and exit.

ENVIRONMENT

       The environment variable PG_COLOR specifies whether to use color in diagnostic messages. Possible values
       are always, auto and never.

SEE ALSO

       postgres(1)

PostgreSQL 16.10                                      2025                                      PG_TEST_FSYNC(1)