Section 1 · User commands

pg_test_fsync.1

Package: postgresql-contrib

PG_TEST_FSYNC

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
ENVIRONMENT
SEE ALSO

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.