Horton

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

Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>

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From: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Kartyshov Ivan <i.kartyshov@postgrespro.ru>, Euler Taveira <euler@eulerto.com>, Thomas Munro <thomas.munro@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, Amit Kapila <amit.kapila16@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Peter Smith <smithpb2250@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2024-04-01T02:25:28Z
Lists: pgsql-hackers 
On Mon, Apr 1, 2024 at 5:54 AM Alexander Korotkov <aekorotkov@gmail.com> wrote:
>
> > 9. To me the following query blocks even though I didn't mention timeout.
> > CALL pg_wal_replay_wait('0/fffffff');
>
> If your primary server is freshly initialized, you need to do quite
> data modifications to reach this LSN.

Right, but why pg_wal_replay_wait  blocks without a timeout? It must
return an error saying it can't reach the target LSN, no?

Did you forget to attach the new patch?

-- 
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

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