PG_TEST_FSYNC(1)

📦 version 16.15, in opensuse-leap 16.0

okay so bestie, welcome to PG_TEST_FSYNC(1) — the PostgreSQL 16.15 docs page that helps you figure out the fastest wal_sync_method for your actual system. It’s giving “disk detective” energy, and we’re gonna get through every flag together. 💅✨

🎀 NAME 🎀

pg_test_fsync — determine fastest wal_sync_method for PostgreSQL.

🦋 SYNOPSIS 🦋

pg_test_fsync [option...]

🌸 DESCRIPTION 🌸

Okay so here’s the whole point: pg_test_fsync is intended to give you a reasonable idea of what the fastest wal_sync_method is on your specific system, and it also supplies diagnostic information in the event of an identified I/O problem.

But bestie, read this part carefully: 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. Cute numbers that actually mean something. ✨

💖 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)

that’s the whole page, bestie — PostgreSQL 16.15, 2026, PG_TEST_FSYNC(1) sign-off, mwah 💋🫶

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