From: | Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> |
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To: | noah(at)leadboat(dot)com |
Cc: | pgsql-hackers(at)postgresql(dot)org, 9erthalion6(at)gmail(dot)com, andrew(dot)dunstan(at)2ndquadrant(dot)com, hlinnaka(at)iki(dot)fi, robertmhaas(at)gmail(dot)com, michael(at)paquier(dot)xyz |
Subject: | Re: [HACKERS] WAL logging problem in 9.4.3? |
Date: | 2019-05-27 05:08:26 |
Message-ID: | 20190527.140826.258215605.horiguchi.kyotaro@lab.ntt.co.jp |
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Lists: | pgsql-hackers |
Thanks for the comment!
At Fri, 24 May 2019 19:33:32 -0700, Noah Misch <noah(at)leadboat(dot)com> wrote in <20190525023332(dot)GE1624191(at)rfd(dot)leadboat(dot)com>
> On Mon, May 20, 2019 at 03:54:30PM +0900, Kyotaro HORIGUCHI wrote:
> > Following this direction, the attached PoC works *at least for*
> > the wal_optimization TAP tests, but doing pending flush not in
> > smgr but in relcache.
>
> This task, syncing files created in the current transaction, is not the kind
> of task normally assigned to a cache. We already have a module, storage.c,
> that maintains state about files created in the current transaction. Why did
> you use relcache instead of storage.c?
The reason was at-commit sync needs buffer flush beforehand. But
FlushRelationBufferWithoutRelCache() in v11 can do
that. storage.c is reasonable as the place.
> On Tue, May 21, 2019 at 09:29:48PM +0900, Kyotaro HORIGUCHI wrote:
> > This is a tidier version of the patch.
>
> > - Move the substantial work to table/index AMs.
> >
> > Each AM can decide whether to support WAL skip or not.
> > Currently heap and nbtree support it.
>
> Why would an AM find it important to disable WAL skip?
The reason is currently it's AM's responsibility to decide
whether to skip WAL or not.
regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center
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