Horton

Re: avoid multiple hard links to same WAL file after a crash

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: tgl@sss.pgh.pa.us, robertmhaas@gmail.com, pgsql-hackers@postgresql.org
Date: 2022-04-12T16:27:42Z
Lists: pgsql-hackers 
On Tue, Apr 12, 2022 at 03:46:31PM +0900, Kyotaro Horiguchi wrote:
> At Mon, 11 Apr 2022 09:52:57 -0700, Nathan Bossart <nathandbossart@gmail.com> wrote in 
>> I traced this back a while ago.  I believe the link() was first added in
>> November 2000 as part of f0e37a8.  This even predates WAL recycling, which
>> was added in July 2001 as part of 7d4d5c0.
> 
> f0e37a8 lacks discussion.. It introduced the CHECKPOINT command from
> somwhere out of the ML.. This patch changed XLogFileInit to
> supportusing existent files so that XLogWrite can use the new segment
> provided by checkpoint and still allow XLogWrite to create a new
> segment by itself.

Yeah, I've been unable to find any discussion besides a brief reference to
adding checkpointing [0].

[0] https://postgr.es/m/8F4C99C66D04D4118F580090272A7A23018D85%40sectorbase1.sectorbase.com

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

Commits

  1. Test restartpoints in archive recovery.

  2. Reset InstallXLogFileSegmentActive after walreceiver self-initiated exit.

  3. Skip WAL recycling and preallocation during archive recovery.

  4. Don't ERROR on PreallocXlogFiles() race condition.

  5. Revert "Add HINT for restartpoint race with KeepFileRestoredFromArchive()."

  6. Remove XLogFileInit() ability to unlink a pre-existing file.

  7. In XLogFileInit(), fix *use_existent postcondition to suit callers.

  8. Remove XLogFileInit() ability to skip ControlFileLock.

  9. Replace durable_rename_excl() by durable_rename(), take two

  10. Add HINT for restartpoint race with KeepFileRestoredFromArchive().

  11. Remove durable_rename_excl()

  12. Replace existing durable_rename_excl() calls with durable_rename()