From: Tom Lane <tgl@sss.pgh.pa.us>
To: Vik Fearing <vik@postgresfriends.org>
cc: zuming.jiang@inf.ethz.ch, pgsql-bugs@lists.postgresql.org,
        Alexander Korotkov <akorotkov@postgresql.org>
Subject: Re: BUG #18170: Unexpected error: no relation entry for relid 3
In-reply-to: <4ecab120-6be3-4cf6-a2a0-249c73ae91d4@postgresfriends.org>
References: <18170-f1d17bf9a0d58b24@postgresql.org>
 <4ecab120-6be3-4cf6-a2a0-249c73ae91d4@postgresfriends.org>
Comments: In-reply-to Vik Fearing <vik@postgresfriends.org>
	message dated "Thu, 26 Oct 2023 17:21:07 +0200"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <1189850.1698340331.1@sss.pgh.pa.us>
Content-Transfer-Encoding: quoted-printable
Date: Thu, 26 Oct 2023 13:12:11 -0400
Message-ID: <1189851.1698340331@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/1189851.1698340331%40sss.pgh.pa.us>
Precedence: bulk

Vik Fearing <vik@postgresfriends.org> writes:
> On 10/26/23 16:01, PG Bug reporting form wrote:
>> My fuzzer finds a bug in Postgres, which triggers an unexpected error.

> This bisects to d3d55ce571369dad6e1d582f1655e5a3fbd8594a, Remove useless=
 =

> self-joins.

I wonder if that new code thinks it can remove ref_2 from the query,
even though ref_2 is used in the targetlist.  I'm not seeing
control reach remove_leftjoinrel_from_query, though.

Also, while nosing around in this, I tried to pprint(root) at the
point of the error, and got

2023-10-26 12:48:37.852 EDT [1186007] WARNING:  could not dump unrecognize=
d node type: 37413808

This happens because the patch changed RelOptInfo.unique_for_rels from
a list of Bitmapsets into a list of UniqueRelInfo, even though it did
not bother to make UniqueRelInfo be a Node type (much less document
the change in globally-visible data structures: pathnodes.h still says
it's a list of Relid sets).  This is not acceptable.

I'm getting the distinct impression that this patch wasn't
ready for prime time.

			regards, tom lane