Horton

Re: [HACKERS] WAL logging problem in 9.4.3?

Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>

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From: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
To: noah@leadboat.com
Cc: pgsql-hackers@postgresql.org, 9erthalion6@gmail.com, andrew.dunstan@2ndquadrant.com, hlinnaka@iki.fi, robertmhaas@gmail.com, michael@paquier.xyz
Date: 2019-05-27T05:08:26Z
Lists: pgsql-hackers 
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

Commits

  1. Add perl2host call missing from a new test file.

  2. Skip WAL for new relfilenodes, under wal_level=minimal.

  3. Revert "Skip WAL for new relfilenodes, under wal_level=minimal."

  4. Back-patch log_newpage_range().

  5. During heap rebuild, lock any TOAST index until end of transaction.

  6. In log_newpage_range(), heed forkNum and page_std arguments.

  7. Back-patch src/test/recovery and PostgresNode from 9.6 to 9.5.

  8. Reduce pg_ctl's reaction time when waiting for postmaster start/stop.

  9. Accelerate end-of-transaction dropping of relations

  10. Redesign the planner's handling of index-descent cost estimation.

  11. Make TRUNCATE do truncate-in-place when processing a relation that was created