WAL

/wahl/ · noun · Development · Origin: 1992

Definitions

  1. Write-Ahead Log — a technique where all modifications are written to a sequential log file before being applied to the actual database pages. If the database crashes, the WAL provides a complete record of committed transactions that can be replayed to recover to a consistent state. WAL is fundamental to ACID guarantees in PostgreSQL, SQLite, and most modern databases.

    In plain English: A diary that a database keeps of every change before actually making it — if the database crashes, it can read the diary to recover everything.

    Example: Replication lag spiked because the replica couldn't consume WAL segments fast enough during the bulk import.

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