Horton

Re: XID formatting and SLRU refactorings (was: Add 64-bit XIDs into PostgreSQL 15)

Aleksander Alekseev <aleksander@timescale.com>

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From: Aleksander Alekseev <aleksander@timescale.com>
To: Postgres hackers <pgsql-hackers@lists.postgresql.org>
Cc: Maxim Orlov <orlovmg@gmail.com>, Japin Li <japinli@hotmail.com>, Andres Freund <andres@anarazel.de>, Peter Geoghegan <pg@bowt.ie>, Michael Paquier <michael@paquier.xyz>, Ian Lawrence Barwick <barwick@gmail.com>, Hamid Akhtar <hamid.akhtar@percona.com>, Pavel Borisov <pashkin.elfe@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Alexander Korotkov <aekorotkov@gmail.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, Ilya Anfimov <ilan@tzirechnoy.com>, Jacob Champion <jchampion@timescale.com>
Date: 2023-01-11T09:22:50Z
Lists: pgsql-hackers 
Hi Maxim,

> Here is a new patch set.
> I've added comments and make use GetClogDirName call in copy_subdir_files.

Jacob Champion pointed out (offlist, cc:'ed) that we may be wrong on this one:

> 0001 patch changes the SLRU internals without affecting the callers.

> 0001 - should make SLRU internally 64–bit, no effects from "outside"

... and apparently Jacob is right.

Besides other things 0001 modifies CLOG_ZEROPAGE and CLOG_TRUNCATE WAL
records - it makes changes to WriteZeroPageXlogRec() and
WriteTruncateXlogRec() and corresponding changes to clog_desc() and
clog_redo().

Firstly, it means that the patch doesn't change what it claims to
change. I think these changes should be part of 0002.

Secondly, shouldn't we introduce a new WAL record type in order to
make the code backward compatible with previous PG versions? I'm not
100% sure how the upgrade procedure works in all the details. If it
requires the DBMS to be gracefully shut down before the upgrade then
we are probably fine here.

-- 
Best regards,
Aleksander Alekseev

Commits

  1. Fix more holes with SLRU code in need of int64 for segment numbers

  2. Use more consistently int64 for page numbers in SLRU-related code

  3. Improve comments in slru.{c,h} about segment name format

  4. Reorder actions in ProcArrayApplyRecoveryInfo()

  5. Fix typo in 5a1dfde8334b

  6. Fix warning due non-standard inline declaration in 4ed8f0913bfdb5f355

  7. Add SLRU tests for 64-bit page case

  8. Make use FullTransactionId in 2PC filenames

  9. Use larger segment file names for pg_notify

  10. Index SLRUs by 64-bit integers rather than by 32-bit integers

  11. Keep track of transaction commit timestamps

  12. Handle 5-char filenames in SlruScanDirectory