Answer
WAL logs all changes before writing data files to ensure durability and enable crash recovery.
Quick Answer
WAL (Write-Ahead Log) records every database change before applying it to data files. On crash, PostgreSQL replays WAL to recover to a consistent state. WAL also enables: replication (WAL is streamed to standbys), point-in-time recovery (restore to any past moment), and logical decoding. WAL files are in pg_wal directory. wal_level setting controls detail level.
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SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ