---
title: "WAL (Write-Ahead Logging) — Database Glossary | Xata"
description: "The mechanism ensuring data durability by writing all changes to a sequential log before applying them to data files. On crash recovery, PostgreSQL repl..."
source: "https://xata.io/glossary/wal"
---

# WAL (Write-Ahead Logging)

WAL

The mechanism ensuring data durability by writing all changes to a sequential log before applying them to data files. On crash recovery, PostgreSQL replays the WAL from the last checkpoint to restore consistency.

Related terms

LSN[Checkpoint](/glossary/checkpoint)[WAL Level](/glossary/wal-level)

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