Answer
Before modifying a data page, SQL writes the log record first. This ensures durability and crash recovery.
Quick Answer
WAL guarantees every change is written to the transaction log (WAL) before it's written to data pages. On crash, SQL Server replays committed log records (redo) and undoes uncommitted ones (undo). This makes the database consistent after a crash without data loss. Durability in ACID depends entirely on WAL.
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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