From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jacob Champion <jacob.champion@enterprisedb.com>
cc: Andrew Dunstan <andrew@dunslane.net>,
        Jelte Fennema-Nio <postgres@jeltef.nl>,
        pgsql-hackers@lists.postgresql.org
Subject: Re: pgsql: libpq: Grease the protocol by default
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Comments: In-reply-to Jacob Champion <jacob.champion@enterprisedb.com>
	message dated "Tue, 24 Feb 2026 14:59:04 -0800"
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Date: Tue, 24 Feb 2026 20:30:29 -0500
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Jacob Champion <jacob.champion@enterprisedb.com> writes:
> Oh, the envvar is clever. You'll probably want to do that only for the
> pg_dumpall invocation now that pg_upgrade is patched, though, so we
> don't cover up regressions.

I can confirm clean x-version tests on all branches with git tip
and this:

--- TestUpgradeXversion.pm.orig 2025-11-25 07:47:25.000000000 -0500
+++ TestUpgradeXversion.pm      2026-02-24 18:50:29.487530840 -0500
@@ -485,10 +485,14 @@ sub test_upgrade    ## no critic (Subrou
 
        # use the NEW pg_dumpall so we're comparing apples with apples.
        setinstenv($self, "$installdir", $save_env);
+       local $ENV{PGMAXPROTOCOLVERSION} =
+         ($oversion le 'REL9_2_STABLE') ? "3.0" : "latest";
+
        system( qq{"$installdir/bin/pg_dumpall" $dump_opts -p $sport -f }
                  . qq{"$upgrade_loc/origin-$oversion.sql" }
                  . qq{> "$upgrade_loc/$oversion-dump1.log" 2>&1});
        return if $?;
+       delete $ENV{PGMAXPROTOCOLVERSION};
        setinstenv($self, "$other_branch/inst", $save_env);
 
        system( qq{"$other_branch/inst/bin/pg_ctl" -D }

which is Andrew's patch but with the envvar dropped as soon
as possible.

			regards, tom lane