Horton

Re: pgsql: libpq: Grease the protocol by default

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jacob Champion <jacob.champion@enterprisedb.com>
Cc: Jelte Fennema-Nio <postgres@jeltef.nl>, pgsql-hackers@lists.postgresql.org, Andrew Dunstan <andrew@dunslane.net>, Nathan Bossart <nathandbossart@gmail.com>
Date: 2026-02-24T18:50:33Z
Lists: pgsql-hackers 
Jacob Champion <jacob.champion@enterprisedb.com> writes:
> So pg_upgrade will use max_protocol_version=3.0 with all servers v10
> and below, in practice. There's nothing wrong with that behavior, but
> I think I should switch to a simple `< 1100` check in the code to
> avoid misleading people, unless anyone has a better way that won't
> significantly increase the cost of the backport.

Simple is good here.  I don't think we'd buy much by distinguishing
minor versions of already-EOL servers.  Also, I suspect that
pg_upgrade can't get the minor version except by starting the server
and asking it --- we don't record anything but major version on-disk.

			regards, tom lane

Commits

  1. pg_upgrade: Use max_protocol_version=3.0 for older servers

  2. libpq: Grease the protocol by default

  3. libpq: Prepare for protocol grease during 19beta