The Wonderful World of WAL
summary
Explains that WAL is the durable change-log that actually contains row bytes (demo: inserted string appears only in WAL until checkpoint), and that replay fixes corrupt on-disk pages for crash recovery and point-in-time recovery; shows commands and tools used: pg_walinspect and function pg_get_wal_records_info, pg_switch_wal, pg_basebackup; demonstrates full-page image for logical replication, unlogged tables produce no WAL, timelines increment on PITR, and replication slots prevent premature WAL recycling.
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chapters (11)
- 0:00Music & introduction
- 0:49Outline, WAL fundamentals & history
- 2:39How WAL works within Postgres
- 4:00Inspecting WAL records with tools
- 7:53Deep dive into WAL record details
- 9:27Crash recovery explained step-by-step
- 15:35Continuous archiving & backups
- 20:58Physical replication overview
- 22:13Logical replication flexibility
- 24:13Replication slots & WAL retention
- 25:35Closing remarks
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