Hazards of logical decoding in PostgreSQL

on YouTube ↗22m

" summary

Explains why logical decoding can blow up disk and CPU: every slot spawns a WalSender that decodes the shared pg_wal stream single‑threaded, uses work_mem and a reorder buffer that spills to disk, and stalled persistent replication slots keep restart_lsn and catalog_xmin from advancing so pg_wal grows. Shows a pg_repack example that writes massive WAL for a temp table that is then filtered away, cites pg_stat_replication_slots and confirmed_flush_lsn for monitoring, warns about Patroni slot re‑creation, and notes a pgJDBC bug that stalled shutdown and hit Debezium.

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" chapters (6)

1. 0:00Intro
2. 2:01Logical decoding
3. 2:59Decoding process
4. 9:44Logical decoding slot
5. 17:46Replication protocol
6. 21:00Conclusion

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