April 4th, 2015 by depesz | Tags: , , , , , , , | Comments Off on Waiting for 9.5 – Add pg_rewind, for re-synchronizing a master server after failback.

On 23rd of March, Heikki Linnakangas committed patch: Add pg_rewind, for re-synchronizing a master server after failback. Earlier versions of this tool were available (and still are) on github. Thanks to Michael Paquier, Alvaro Herrera, Peter Eisentraut, Amit Kapila, and Satoshi Nagayasu for review.

One of my clients is upgrading some servers. The procedure we have took some time to get to current state, and we found some potential problems, so decided to write more about it.

I had to deal with this question, or some version of it, quite a few times. So, decided to write a summary on what one could (or should) do, after data is in database, and application is running. Namely - ...

On 25th of January, Simon Riggs committed patch: Allow pg_basebackup from standby node with safety checking. Base backup follows recommended procedure, plus goes to great lengths to ensure that partial page writes are avoided. Jun Ishizuka and Fujii Masao, with minor modifications

On 19th of July, Simon Riggs committed patch: Cascading replication feature for streaming log-based replication. Standby servers can now have WALSender processes, which can work with either WALReceiver or archive_commands to pass data. Fully updated docs, including new conceptual terms of sending server, upstream ...

Well, the biggest information is that hot-backups on slave work. And they work fine. Really fine. Some more information (with nice graph!):