Databases · Senior · Question 4 of 75

What is the purpose of the write-ahead log (WAL)?

1It stores a backup of each table every hour
✓Correct answer: Changes are written to a sequential log and flushed before commit, so the database can recover after a crash and stream changes to replicas
3It logs all SELECT queries for auditing

Explanation

Data pages can be written to disk later in the background. WAL also powers physical replication, logical decoding and point-in-time recovery.

Further reading

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