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  1. Debezium
  2. DBZ-1530

Documentation Inaccuracies

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      I have found an apparent inaccuracy in Debezium documentation for Postgres that should clarified. I can make a PR myself as long as I'm not missing something...

      Under https://debezium.io/documentation/reference/0.10/connectors/postgresql.html#output-plugin (https://github.com/debezium/debezium/blob/master/documentation/modules/ROOT/pages/connectors/postgresql.adoc) it says:


      Debezium needs a PostgreSQL’s WAL to be kept during Debezium outages. If your WAL retention is too small and outages too long then Debezium will not be able to recover after restart as it will miss part of the data changes. The usual indicator is an error similar to this thrown during the startup: ERROR: requested WAL segment 000000010000000000000001 has already been removed.

      This is simply not true because Debezium uses replication slots, which means Postgres absolutely will not remove WAL that Debezium needs..... even if it's down for days:
      https://www.postgresql.org/docs/current/warm-standby.html#STREAMING-REPLICATION-SLOTS

      There is lots of other language in this docs page indicating the same thing, apparently without any reference to the fact that the replication slot will hold WAL indefinitely...

      Please let me know if I am missing something else. Thanks.

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            jfinzel Jeremy Finzel
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