Re: "Multiple table synchronizations are processed serially" still happens

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Guillaume Lelarge <guillaume(at)lelarge(dot)info>
Cc: PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: "Multiple table synchronizations are processed serially" still happens
Date: 2021-05-21 03:43:40
Message-ID: CAA4eK1J8jiskPQ_CEk_wf52o7eMzawsnuLY1WfBhaHvZT7x0vw@mail.gmail.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

On Fri, May 21, 2021 at 1:30 AM Guillaume Lelarge
<guillaume(at)lelarge(dot)info> wrote:
>
>
>> If so, the
>> problem might be that copying the data of the first table creates a
>> transaction which blocks creation of the slot for second table copy.
>
>
> I don't understand how a transaction could block the creation of a slot. Could you explain that to me?
>

During the creation of the slot, we need to build the initial snapshot
which is used for decoding WAL. Now, to build the initial snapshot, we
wait for all running xacts to finish. See functions
CreateReplicationSlot() and SnapBuildFindSnapshot().

--
With Regards,
Amit Kapila.

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Masahiro Ikeda 2021-05-21 03:45:46 Re: Transactions involving multiple postgres foreign servers, take 2
Previous Message Amit Kapila 2021-05-21 03:33:13 Re: multi-install PostgresNode fails with older postgres versions