PG_TEST_FSYNC(1)         PostgreSQL 16.2 Documentation        PG_TEST_FSYNC(1)

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 16.2                      2024                     PG_TEST_FSYNC(1)