Re: [HACKERS] Logical replication and synchronous replication

On 18 April 2017 at 18:55, Masahiko Sawada <sawada.mshk@gmail.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