Re: Patch for fail-back without fresh backup
| От | Jeff Janes |
|---|---|
| Тема | Re: Patch for fail-back without fresh backup |
| Дата | |
| Msg-id | CAMkU=1zNE0DzFgKi9J+czJCcium2vLESP_KFy5y_Jr37onQPgQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Patch for fail-back without fresh backup (Andres Freund <andres@2ndquadrant.com>) |
| Ответы |
Re: Patch for fail-back without fresh backup
|
| Список | pgsql-hackers |
On Thu, Nov 21, 2013 at 2:43 PM, Andres Freund <andres@2ndquadrant.com> wrote:
On 2013-11-21 14:40:36 -0800, Jeff Janes wrote:We short circuit that if there's no xid assigned. Check
> But if the transaction would not have otherwise generated WAL (i.e. a
> select that did not have to do any HOT pruning, or an update with zero rows
> matching the where condition), doesn't it now have to flush and wait when
> it would otherwise not?
RecordTransactionCommit().
It looks like that only short-circuits the flush if both there is no xid assigned, and !wrote_xlog. (line 1054 of xact.c)
I do see stalls on fdatasync on flush from select statements which had no xid, but did generate xlog due to HOT pruning, I don't see why WAL logging hint bits would be different.
Cheers,
Jeff
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