3 thoughts on “pg_rewind, a tool for resynchronizing after failover

  1. Cool, Heikki.

    After failing back, does the slave need to be recreated? Or does that depend on 9.4 timeline changes?

  2. very userful, is there any plan for make pg_rewind compatible with 9.1/9.2 tree?
    is there any plan for that?

    • No plans to do that. 9.3 made it easier to write tools like this, thanks to a patch by Andres Freund to split the WAL reading code into a separate file that can be used in external tools. For older versions, all that code would need to be copy-pasted and modified to work without all the backend infrastructure.

      Also, Robert Haas pointed out a fairly serious flaw in pg_rewind: http://www.postgresql.org/message-id/CA+TgmoY4j+p7JY69ry8GpOSMMdZNYqU6dtiONPrcxaVG+SPByg@mail.gmail.com. Fortunately, that problem can be avoided by turning on page checksums, which forces full-page images to be written to WAL for hint bit updates. That makes pg_rewind safe again. But page checksums is a new feature in 9.3.

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