Re: Replication protocol doc fix

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Replication protocol doc fix
Date: 2021-06-11 22:12:29
Message-ID: 25346d82854bfe37b2fb4695613969fdf8a5216d.camel@j-davis.com
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On Fri, 2021-06-11 at 16:57 -0400, Robert Haas wrote:
> My impression was that CopyBoth can be initiated either way,

The docs say: "In either physical replication or logical replication
walsender mode, only the simple query protocol can be used." Is there
some way to initiate CopyBoth outside of walsender?

> but if
> you use the extended query protocol, then the result is a hopeless
> mess, because the protocol is badly designed:
>
>
https://www.postgresql.org/message-id/CA+Tgmoa4eA+cPXaiGQmEBp9XisVd3ZE9dbvnbZEvx9UcMiw2tg@mail.gmail.com

It seems like you're saying that CopyIn and CopyBoth are both equally
broken in extended query mode. Is that right?

> But I think you're correct in saying that the discard-until-Sync
> behavior only happens if the extended query protocol is used, so I
> agree that the current text is wrong.

Should we just document how CopyBoth works with the simple query
protocol, or should we make it match the CopyIn docs?

Regards,
Jeff Davis

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