Horton

Re: pgsql: libpq: Grease the protocol by default

Jelte Fennema-Nio <postgres@jeltef.nl>

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From: Jelte Fennema-Nio <postgres@jeltef.nl>
To: Jacob Champion <jacob.champion@enterprisedb.com>
Cc: Jacob Champion <jchampion@postgresql.org>, pgsql-committers@lists.postgresql.org
Date: 2026-02-23T22:24:34Z
Lists: pgsql-hackers 
On Mon, 23 Feb 2026 at 22:17, Jacob Champion
<jacob.champion@enterprisedb.com> wrote:
> So while this is kind of a nice result, in that it's correctly
> diagnosing the problem, I need to add max_protocol_version=3.0 to the
> connection strings for these upgrades during beta.

Two thoughts:
1. I think we might want the "This indicates a bug in either the
server being contacted..." note to be added to the error even if you
use 3.2/3.3/3.X. It seems pretty helpful in general. It would need a
bit fancier detection though, with strings to search for based on the
actual requested version.
2. Why only force max_protocol_version=3.0 for beta? It sounds like
this would also be an issue once we eventually bump the default
version.

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