From: Tom Lane <tgl@sss.pgh.pa.us>
To: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
cc: elprans@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #17363: 14 regression: "could not identify a hash function
 for type record" in a nested record in sublink
In-reply-to: <2998707.1642001695@sss.pgh.pa.us>
References: <17363-f6d42fd0d726be02@postgresql.org>
 <2998707.1642001695@sss.pgh.pa.us>
Comments: In-reply-to Tom Lane <tgl@sss.pgh.pa.us>
	message dated "Wed, 12 Jan 2022 10:34:55 -0500"
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Date: Sun, 16 Jan 2022 16:00:44 -0500
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 <https://www.postgresql.org/message-id/3820408.1642366844%40sss.pgh.pa.us>
Precedence: bulk

I wrote:
> It appears that we're trying to use a hashed subplan for the =ANY,
> where v13 did not.  So I'm inclined to blame this on 01e658fa7 (Hash
> support for row types).  We backed off the optimism level a bit in
> a3d2b1bbe (Disable anonymous record hash support except in special
> cases), but evidently didn't go far enough; or else it's doing the
> wrong thing for nested RECORD types.

Ugh, found it: hash_ok_operator() is not accounting for this case.

    if (opid == ARRAY_EQ_OP)
    {
        /* array_eq is strict, but must check input type to ensure hashable */
        /* XXX record_eq will need same treatment when it becomes hashable */
        Node       *leftarg = linitial(expr->args);

        return op_hashjoinable(opid, exprType(leftarg));
    }

Will fix.

			regards, tom lane