Horton

Re: Avoid erroring out when unable to remove or parse logical rewrite files to save checkpoint work

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, "Bossart, Nathan" <bossartn@amazon.com>, Tom Lane <tgl@sss.pgh.pa.us>, Julien Rouhaud <rjuju123@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-02-04T00:03:40Z
Lists: pgsql-hackers 
On Thu, Feb 03, 2022 at 09:45:08AM +0530, Bharath Rupireddy wrote:
> On Thu, Feb 3, 2022 at 12:07 AM Nathan Bossart <nathandbossart@gmail.com> wrote:
>> If there is a problem reading the directory, we will LOG and then exit the
>> loop.  If we didn't scan through all the entries in the directory, there is
>> a chance that we didn't fsync() all the files that need it.
> 
> Thanks. I get it. For syncing map files, we don't want to tolerate any
> errors, whereas removal of the old map files (lesser than cutoff LSN)
> can be tolerated in CheckPointLogicalRewriteHeap.

LGTM.  Andres noted upthread [0] that the comment above sscanf() about
skipping editors' lock files might not be accurate.  I don't think it's a
huge problem if sscanf() matches those files, but perhaps we can improve
the comment.

[0] https://postgr.es/m/20220120194618.hmfd4kxkng2cgryh%40alap3.anarazel.de

-- 
Nathan Bossart
Amazon Web Services: https://aws.amazon.com

Commits

  1. Expand the use of get_dirent_type(), shaving a few calls to stat()/lstat()

  2. fsync pg_logical/mappings in CheckPointLogicalRewriteHeap().

  3. Introduce logical decoding.