3 / 6 CDC, Outbox & Event Sourcing

Slot Machine

A Debezium Postgres connector has been stopped for a two-day maintenance window. Write volume is normal, yet pg_wal on the primary keeps growing and the instance is close to running out of disk. What is the cause?

A

The connector's initial snapshot writes its own copy of every scanned row back into the WAL, and that snapshot never completed before the maintenance window began

B

The connector's inactive logical replication slot still pins its restart position, so Postgres cannot recycle any WAL segment written since the connector stopped

C

Setting wal_level to logical roughly doubles the volume of WAL written per transaction, so two ordinary days of traffic produced more than the disk could hold

D

A long-running transaction is holding back the vacuum horizon, which forces Postgres to keep every WAL segment written since that transaction began