On 24 October 2017 at 09:50, Tom Lane <t...@sss.pgh.pa.us> wrote: > Simon Riggs <si...@2ndquadrant.com> writes: >> Remove the code that maintained two checkpoint's WAL files and all >> associated stuff. > >> Try to avoid breaking anything else > >> This >> * reduces disk space requirements on master >> * removes a minor bug in fast failover >> * simplifies code > > Doesn't it also make crash recovery less robust? The whole point > of that mechanism is to be able to cope if the latest checkpoint > record is unreadable. If you want to toss that overboard, I think > you need to make the case why we don't need it, not just post a > patch removing it. *Of course* the code is simpler without it. > That's utterly irrelevant. The code would be even simpler with > no crash recovery at all ... but we're not going there.
Well, the mechanism has already been partially removed since we don't maintain two checkpoints on a standby. So all I'm proposing is we remove the other half. I've not seen myself, nor can I find an example online where the primary failed yet the secondary did not also fail from the same cause. If it is a possibility to do this, now we have pg_waldump we can easily search for a different checkpoint and start from there instead which is a more flexible approach. If you didn't save your WAL and don't have any other form of backup, relying on the secondary checkpoint is not exactly a safe bet. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers