sqlite-wal-end-mark · shipping · also WAL reader end mark

SQLite WAL end mark

A SQLite WAL end mark is the committed WAL boundary that determines which page versions a read transaction may observe.

Related Observatory article: SQLite WAL end mark on hesela.com

The transaction's snapshot does not advance when another connection commits. Ending the transaction and starting another permits a newer view. [1] Distinguish this logical snapshot boundary from the shared WAL-index read-mark slots and locks used by checkpoint coordination. They are related mechanisms, not interchangeable counters. [2] Our complete row oracle checks the retained generation and the newer state after release. [4]

Relations

related

write-ahead-log, database-checkpoint, checkpoint-starvation

Limitations

• An open connection does not itself identify the lifetime or contents of an active read snapshot. [1]

Citations

1. SQLite: Isolation, WAL snapshots and transaction lifetime (accessed 2026-10-14)
2. SQLite: WAL-mode File Format, WAL-index header and read marks (accessed 2026-10-14)
3. SQLite WAL checkpoint starvation: success is not completion (accessed 2026-10-14)
4. Hesela: measured SQLite WAL-reader observations and limits (accessed 2026-10-14)

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