Horton

Re: Logical replication timeout problem

Fabrice Chapuis <fabrice636861@gmail.com>

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From: Fabrice Chapuis <fabrice636861@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Tang, Haiying/唐 海英 <tanghy.fnst@fujitsu.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-01-13T10:13:02Z
Lists: pgsql-hackers 
first phase: postgres read WAL files and generate 1420 snap files.
second phase: I guess, but on this point maybe you can clarify, postgres
has to decode the snap files and remove them if no statement must be
applied on a replicated table.
It is from this point that the worker process exit after 1 minute timeout.

On Wed, Jan 12, 2022 at 11:54 AM Amit Kapila <amit.kapila16@gmail.com>
wrote:

> On Tue, Jan 11, 2022 at 8:13 PM Fabrice Chapuis <fabrice636861@gmail.com>
> wrote:
>
>> Can you explain why you think this will help in solving your current
>> problem?
>>
>> Indeed your are right this function won't help, we have to look elsewhere.
>>
>> It is still not clear to me why the problem happened? IIUC, after
>> restoring 4096 changes from snap files, we send them to the subscriber, and
>> then apply worker should apply those one by one. Now, is it taking one
>> minute to restore 4096 changes due to which apply worker is timed out?
>>
>> Now I can easily reproduce the problem.
>> In a first phase, snap files are generated and stored in pg_replslot.
>> This process end when1420 files are present in pg_replslots (this is in
>> relation with statements that must be replayed from WAL). In the
>> pg_stat_replication view, the state field is set to *catchup*.
>> In a 2nd phase, the snap files must be decoded. However after one minute
>> (wal_receiver_timeout parameter set to 1 minute) the worker process stop
>> with a timeout.
>>
>>
> What exactly do you mean by the first and second phase in the above
> description?
>
> --
> With Regards,
> Amit Kapila.
>

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