Date: Wed, 13 May 2020 11:15:18 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: noah@leadboat.com, pgsql-hackers@postgresql.org
Subject: Re: PG 13 release notes, first draft
Message-ID: <20200513151518.GA20111@momjian.us>
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On Wed, May 13, 2020 at 11:56:33AM +0900, Kyotaro Horiguchi wrote:
> > 
> > 	Allow skipping of WAL for new tables and indexes if wal_level is
> > 	'minimal' (Kyotaro Horiguchi)
> > 
> > 	Relations larger than wal_skip_threshold will have their files
> > 	fsync'ed rather than writing their WAL records.  Previously this
> > 	was done only for COPY operations, but the implementation had a
> > 	bug that could cause data loss during crash recovery.
> 
> I see it. It is giving weight on improvement. Looks good the overall
> structure of the description above.  However, wal-skipping is always
> done regardless of table size. wal_skip_threshold is an optimization
> to choose which to use fsync or FPI records (that is, not WAL records
> in the common sense) at commit for speed.

Well, as far as users are concerned, everything wrtiten to  WAL is a WAL
record.

> So how about the following?
> 
> All kinds of bulk-insertion are not WAL-logged then fsync'ed at
> commit.  Using FPI WAL records instead of fsync for relations smaller
> than wal_skip_threshold. Previously this was done only for COPY
> operations and always using fsync, but the implementation had a bug
> that could cause data loss during crash recovery.

That is too much detail for the release notes.  We already will link to
the docs.  Why put it here?

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EnterpriseDB                             https://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +