Horton

Re: [HACKERS] make async slave to wait for lsn to be replayed

Ivan Kartyshov <i.kartyshov@postgrespro.ru>

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From: Картышов Иван <i.kartyshov@postgrespro.ru>
To: "Alexander Korotkov" <aekorotkov@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2023-11-20T11:10:43Z
Lists: pgsql-hackers

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Alexander, thank you for your review and pointing this issues. According to
them I made some fixes and rebase all patch.

But I can`t repeat your ERROR. Not with hot_standby_feedback = on nor 
hot_standby_feedback = off.master: create table test as (select i from generate_series(1,10000) i);
slave conn1: select pg_wal_replay_pause();
master: delete from test;
master: vacuum test;
master: select pg_current_wal_lsn();
slave conn2: select pg_wait_lsn('the value from previous query'::pg_lsn, 0);
slave conn1: select pg_wal_replay_resume();
slave conn2: ERROR: canceling statement due to conflict with recovery
DETAIL: User query might have needed to see row versions that must be removed.Also I use little hack to work out of snapshot similar to SnapshotResetXmin.

Patch rebased and ready for review.


 

Commits

  1. Ensure standby promotion point in 043_wal_replay_wait.pl

  2. Minor cleanup related to pg_wal_replay_wait() procedure

  3. Adjust pg_wal_replay_wait() procedure behavior on promoted standby

  4. pg_wal_replay_wait(): Fix typo in the doc

  5. Implement pg_wal_replay_wait() stored procedure

  6. Revert: Implement pg_wal_replay_wait() stored procedure

  7. Call WaitLSNCleanup() in AbortTransaction()

  8. Clarify what is protected by WaitLSNLock

  9. Use an LWLock instead of a spinlock in waitlsn.c

  10. Use the pairing heap instead of a flat array for LSN replay waiters

  11. Minor improvements for waitlsn.c

  12. Make the order of the header file includes consistent