Re: [PATCHES] Restartable Recovery
От | Simon Riggs |
---|---|
Тема | Re: [PATCHES] Restartable Recovery |
Дата | |
Msg-id | 1155124089.2368.87.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | Re: [PATCHES] Restartable Recovery (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | pgsql-hackers |
On Mon, 2006-08-07 at 13:05 -0400, Tom Lane wrote: > Simon Riggs <simon@2ndquadrant.com> writes: > > I've implemented this for BTree, GIN, GIST using an additional rmgr > > function bool rm_safe_restartpoint(void) > > ... > > "Recovery checkpoints" are now renamed "restartpoints" to avoid > > confusion with checkpoints. So checkpoints occur during normal > > processing (only) and restartpoints occur during recovery (only). > > Applied with revisions. err....CheckPointGuts() :-) I guess patch reviews need some spicing up. > As submitted the patch pushed backup_label out > of the way immediately upon reading it, which is no good: you need to be > sure that the starting checkpoint location is written to pg_control > first, else an immediate crash would allow the thing to try to start > from whatever checkpoint is listed in the backed-up pg_control. Also, > the minimum recovery stopping point that's obtained using the label file > still has to be enforced if there's a crash during the replay sequence. > I felt the best way to do that was to copy the minimum stopping point > into pg_control, so that's what the code does now. Thanks for checking that. > Also, as I mentioned earlier, I think that doing restartpoints on the > basis of elapsed time is simpler and more useful than having an explicit > distinction between "normal" and "standby" modes. We can always invent > a standby_mode flag later if we need one, but we don't need it for this. OK, agreed. The original thinking was that writing a restartpoint was more crucial when in standby mode; but this way we've better performance and have a low ceiling on the restart time if that should ever occur at the worst moment. Thanks again to Marko for the concept. I'll work on the docs for backup.sgml also. -- Simon Riggs EnterpriseDB http://www.enterprisedb.com
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