Horton

RE: Logical replication timeout problem

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "kuroda.hayato@fujitsu.com" <kuroda.hayato@fujitsu.com>
To: "wangw.fnst@fujitsu.com" <wangw.fnst@fujitsu.com>
Cc: Fabrice Chapuis <fabrice636861@gmail.com>, Simon Riggs <simon.riggs@enterprisedb.com>, Petr Jelinek <petr.jelinek@enterprisedb.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Ajin Cherian <itsajin@gmail.com>, Peter Smith <smithpb2250@gmail.com>
Date: 2022-03-08T08:47:32Z
Lists: pgsql-hackers 
Dear Wang,

Thank you for updating the patch! Good self-reviewing.

> And I looked into the function WalSndUpdateProgress. I found function
> WalSndUpdateProgress try to record the time of some message(by function
> LagTrackerWrite) sent to subscriber, such as in function pgoutput_commit_txn.

Yeah, I think you are right.

> Then, when publisher receives the reply message from the subscriber(function
> ProcessStandbyReplyMessage), publisher invokes LagTrackerRead to calculate
> the
> delay time(refer to view pg_stat_replication).
> Referring to the purpose of LagTrackerWrite, I think it is no need to log time
> when sending keepalive messages here.
> So when the parameter send_keep_alive of function WalSndUpdateProgress is
> true,
> skip the recording time.

I also read them. LagTracker records the elapsed time between sending commit
from publisher and receiving reply from subscriber, right? It seems good.

Do we need adding a test for them? I think it can be added to 100_bugs.pl.
Actually I tried to send PoC, but it does not finish to implement that.
I'll send if it is done.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED

Commits

  1. Fix the logical replication timeout during large DDLs.

  2. Fix the logical replication timeout during large transactions.

  3. Rethink the delay-checkpoint-end mechanism in the back-branches.

  4. Revert "Logical decoding of sequences"

  5. Skip empty transactions for logical replication.

  6. Allow specifying column lists for logical replication

  7. Add decoding of sequences to built-in replication

  8. Fix ABI break introduced by commit 4daa140a2f.

  9. Lag tracking for logical replication