Write-ahead log

Every change is appended to a log before being applied, so a crash can be recovered by replaying it. The same log feeds replication and change data capture.

Where it shows up in real systems

  • Change data capture

    Keeps search indexes, caches and warehouses in sync without dual writes in the application, which can drift when one write fails. Consumers see changes a fraction of a second later.

    In production: Debezium, AWS DMS, Kafka Connect, Google Datastream, Fivetran

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