PG_TEST_FSYNC(1)

💅 pg_test_fsync(1) — determine fastest wal_sync_method for PostgreSQL ✨

🌸 NAME 🌸

pg_test_fsync is here to help you determine the fastest wal_sync_method for PostgreSQL, bestie. That’s the whole assignment, and it’s honestly iconic. 💖

✨ SYNOPSIS ✨

pg_test_fsync [option...]

Yep, that’s the vibe: pg_test_fsync [option...]. Options are optional, results are not. 💅

🦋 DESCRIPTION 🦋

okay so, 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. Useful? Very. Magical? Not exactly. 🌈

However — important reality check — 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. So don’t let the numbers have main character energy without context, fr fr. 💀

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. Numbers with a purpose, we love to see it. 🔥

🎀 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. Simple, clean, slay. 👑
• -?, --help — Show help about pg_test_fsync command line arguments, and exit. Your little map when you need it. 🗺️

🌈 ENVIRONMENT 🌈

The environment variable PG_COLOR specifies whether to use color in diagnostic messages. Possible values are always, auto and never. Cute messages, but make them color-coded if you want. 🎨

🫶 SEE ALSO 🫶

postgres(1) — go say hi to the main character. 💜

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That’s the whole page, bestie 💖✨ Source/version vibes: PostgreSQL 15.19 Documentation; date vibes: 2026; manual-name vibes: PG_TEST_FSYNC(1). Byeee 🫶🎀