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Re: cleanup patches for incremental backup

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Alexander Lakhin <exclusion@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Matthias van de Meent <boekewurm+postgres@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-01-29T18:21:30Z
Lists: pgsql-hackers 
On Sat, Jan 27, 2024 at 10:31:09AM -0600, Nathan Bossart wrote:
> On Sat, Jan 27, 2024 at 11:00:01AM +0300, Alexander Lakhin wrote:
>> I'm discouraged by "\n1" in the file name and in the
>> "examining summary..." message.
>> regress_log_002_blocks from the following successful test run on the same
>> sungazer node contains:
>> [15:21:58.924](0.106s) # examining summary for TLI 1 from 0/155BAE0 to 0/155E750
>> [15:21:58.925](0.001s) ok 1 - WAL summary file exists
> 
> Ah, I think this query:
> 
> 	SELECT tli, start_lsn, end_lsn from pg_available_wal_summaries()
> 		WHERE tli = $summarized_tli AND end_lsn > '$summarized_lsn'
> 
> is returning more than one row in some cases.  I attached a quick sketch of
> an easy way to reproduce the issue as well as one way to fix it.

The buildfarm just caught a failure with the new logging in place:

	https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=calliphoridae&dt=2024-01-29%2018%3A09%3A10

I'm not totally sure my "fix" is correct, but I think this does confirm the
theory.

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

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Avoid overflow in MaybeRemoveOldWalSummaries().

  2. Revert "Temporary patch to help debug pg_walsummary test failures."

  3. Revise pg_walsummary's 002_blocks test to avoid spurious failures.

  4. Temporary patch to help debug pg_walsummary test failures.

  5. More documentation updates for incremental backup.

  6. Fix typos.

  7. Fix typo.

  8. Try to fix pg_walsummary buildfarm failures.

  9. Repair various defects in dc212340058b4e7ecfc5a7a81ec50e7a207bf288.

  10. Add new pg_walsummary tool.

  11. Add new function pg_get_wal_summarizer_state().

  12. Document WAL summarization information functions.