From: | Craig Ringer <craig(at)2ndquadrant(dot)com> |
---|---|
To: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Logical replication and synchronous replication |
Date: | 2017-04-18 12:05:55 |
Message-ID: | CAMsr+YFvHP8_xWBeMzzx1nz_5gfz+dW4dNNwQHqA7j1RUTX6tw@mail.gmail.com |
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Lists: | pgsql-hackers |
On 18 April 2017 at 18:55, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> Hi,
>
> As doc of logical decoding said as a note[1], logical replication can
> support the synchronous replication with some restriction. But In
> addition to this, IIUC in logical replication decoded data is sent to
> subscribers only when the commit WAL record is decoded (calls
> ReorderBufferCommit) .
Correct.
> It means that the local SQL execution and
> applying the decoded data on subscriber side are always executed in a
> sequential order, and the response time can simply be doubled or even
> more (OTOH a good point is that decoded data of aborted transaction is
> never sent to subscriber). I think there will be a lot of peoples who
> want to use logical synchronous replication but this is a big
> restriction for such user. I think we should document it or deal with
> it.
> Thought?
Definitely should be documented. I think it's covered under logical
decoding, but needs at least an xref.
--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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