Horton

Re: logical replication empty transactions

Ajin Cherian <itsajin@gmail.com>

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From: Ajin Cherian <itsajin@gmail.com>
To: "osumi.takamichi@fujitsu.com" <osumi.takamichi@fujitsu.com>
Cc: Peter Smith <smithpb2250@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, vignesh C <vignesh21@gmail.com>, Michael Paquier <michael@paquier.xyz>, Rahila Syed <rahila.syed@2ndquadrant.com>, Euler Taveira <euler@timbira.com.br>, Dilip Kumar <dilipbalaut@gmail.com>, Jeff Janes <jeff.janes@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Craig Ringer <craig@2ndquadrant.com>
Date: 2022-02-18T08:21:49Z
Lists: pgsql-hackers 
On Wed, Feb 16, 2022 at 2:15 PM osumi.takamichi@fujitsu.com
<osumi.takamichi@fujitsu.com> wrote:
> Another idea would be, to create an empty file under the the pg_replslot/slotname
> with a prefix different from "xid"  in the DecodePrepare before the shutdown
> if the prepare was empty, and bypass the cleanup of the serialized txns
> and check the existence after the restart. But, this is pretty ad-hoc and I wasn't sure
> if to address the corner case of the restart has the strong enough justification
> to create this new file format.
>

Yes, this doesn't look very efficient.

> Therefore, in my humble opinion, the idea of protocol change slightly wins,
> since the impact of the protocol change would not be big. We introduced
> the protocol version 3 in the devel version and the number of users should be little.

Yes, but we don't want to break backward compatibility for this small
added optimization.

Amit,

I will work on your comments.

regards,
Ajin Cherian
Fujitsu Australia

Commits

  1. Skip empty transactions for logical replication.

  2. Add decoding of sequences to built-in replication

  3. Allow specifying row filters for logical replication of tables.