Re: Allow an alias to be attached directly to a JOIN ... USING

From: Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Allow an alias to be attached directly to a JOIN ... USING
Date: 2019-12-24 18:13:32
Message-ID: alpine.DEB.2.21.1912241908490.27864@pseudo
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On Tue, 17 Sep 2019, Alvaro Herrera wrote:

>> Indeed, that seems like a problem, and it's a good question. You can
>> see this on unpatched master with SELECT x.filler FROM
>> (pgbench_tellers AS t JOIN b USING (bid)) AS x.
>
> I'm not sure I understand why that problem is a blocker for this patch.

As discussed on another thread,

https://www.postgresql.org/message-id/flat/2aa57950-b1d7-e9b6-0770-fa592d565dda(at)2ndquadrant(dot)com

the patch does not conform to spec

SQL:2016 Part 2 Foundation Section 7.10 <joined table>

Basically "x" is expected to include *ONLY* joined attributes with USING,
i.e. above only x.bid should exists, and per-table aliases are expected to
still work for other attributes.

ISTM that this patch could be "returned with feedback".

--
Fabien.

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