From: Tom Lane <tgl@sss.pgh.pa.us>
To: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Missing MaterialPath support in reparameterize_path_by_child
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Comments: In-reply-to Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
	message dated "Tue, 06 Dec 2022 20:07:57 +0530"
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Date: Tue, 06 Dec 2022 09:52:51 -0500
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Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> writes:
> On Mon, Dec 5, 2022 at 8:13 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I don't especially like "rel->nparts = 0" as a way of disabling
>> partitionwise join ...

> ... If we can not generate AppendPath for a
> join relation, it means there is no way to compute child join
> relations and thus the relation is not partitioned. So setting
> rel->nparts = 0 is right.

If we had nparts > 0 before, then it is partitioned for some value
of "partitioned", so I don't entirely buy this argument.

> Probably we should add macros similar to
> dummy relation for marking and checking partitioned relation. I see
> IS_PARTITIONED_RELATION() is defined already. Maybe we could add
> mark_(un)partitioned_rel().

Hiding it behind a macro with an explanatory name would be an
improvement, for sure.

			regards, tom lane