Re: [HACKERS] WAL logging problem in 9.4.3?

Thanks for the comment!

At Fri, 24 May 2019 19:33:32 -0700, Noah Misch <noah@leadboat.com> wrote in
<20190525023332.GE1624191@rfd.leadboat.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