Horton

Re: Implement waiting for wal lsn replay: reloaded

Xuneng Zhou <xunengzhou@gmail.com>

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From: Xuneng Zhou <xunengzhou@gmail.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Álvaro Herrera <alvherre@alvh.no-ip.org>, Tomas Vondra <tomas@vondra.me>, Yura Sokolov <y.sokolov@postgrespro.ru>, pgsql-hackers@lists.postgresql.org
Date: 2025-08-27T15:54:25Z
Lists: pgsql-hackers

Commits

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

  1. Clean up 019_replslot_limit.pl comments

  2. Stabilize 019_replslot_limit.pl: wait on slot restart_lsn

  3. Use WAIT FOR LSN in PostgreSQL::Test::Cluster::wait_for_catchup()

  4. Add tab completion for the WAIT FOR LSN MODE option

  5. Add the MODE option to the WAIT FOR LSN command

  6. Extend xlogwait infrastructure with write and flush wait types

  7. Unify error messages

  8. Optimize shared memory usage for WaitLSNProcInfo

  9. Fix WaitLSNWakeup() fast-path check for InvalidXLogRecPtr

  10. Fix incorrect function name in comments

  11. Add infrastructure for efficient LSN waiting

  12. Add pairingheap_initialize() for shared memory usage

  13. Implement WAIT FOR command

Attachments

Hi all,

I did a rebase for the patch to v8 and incorporated a few changes:

1) Updated documentation, added new tests, and applied minor code
adjustments based on prior review comments.
2) Tweaked the initialization of waitReplayLSNState so that
non-backend processes can call wait for replay.

Started a new thread [1] and attached a patch addressing the polling
issue in the function
read_local_xlog_page_guts built on the infra of patch v8.

[1] https://www.postgresql.org/message-id/CABPTF7Vr99gZ5GM_ZYbYnd9MMnoVW3pukBEviVoHKRvJW-dE3g@mail.gmail.com

Feedbacks welcome.

Best,
Xuneng