Re: Bogus WAL segments archived after promotion
От | Heikki Linnakangas |
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Тема | Re: Bogus WAL segments archived after promotion |
Дата | |
Msg-id | 552BD95B.1070802@iki.fi обсуждение исходный текст |
Ответ на | Re: Bogus WAL segments archived after promotion (Bruce Momjian <bruce@momjian.us>) |
Ответы |
Re: Bogus WAL segments archived after promotion
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Список | pgsql-hackers |
On 04/01/2015 07:12 PM, Bruce Momjian wrote: > On Fri, Dec 19, 2014 at 10:26:34PM +0200, Heikki Linnakangas wrote: >> On 12/19/2014 02:55 PM, Heikki Linnakangas wrote: >>> I'm thinking that we should add a step to promotion, where we scan >>> pg_xlog for any segments higher than the timeline switch point, and >>> remove them, or mark them with .done so that they are not archived. >>> There might be some real WAL that was streamed from the primary, but not >>> yet applied, but such WAL is of no interest to that server anyway, after >>> it's been promoted. It's a bit disconcerting to zap WAL that's valid, >>> even if doesn't belong to the current server's timeline history, because >>> as a general rule it's good to avoid destroying evidence that might be >>> useful in debugging. There isn't much difference between removing them >>> immediately and marking them as .done, though, because they will >>> eventually be removed/recycled anyway if they're marked as .done. >> >> This is what I came up with. This patch removes the suspect segments >> at timeline switch. The alternative of creating .done files for them >> would preserve more evidence for debugging, but OTOH it would also >> be very confusing to have valid-looking WAL segments in pg_xlog, >> with .done files, that in fact contain garbage. >> >> The patch is a bit longer than it otherwise would be, because I >> moved the code to remove a single file from RemoveOldXlogFiles() to >> a new function. I think that makes it more readable in any case, >> simply because it was so deeply indented in RemoveOldXlogFiles. > > Where are we on this? I didn't hear any better ideas, so committed this now. - Heikki
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