From: Tom Lane <tgl@sss.pgh.pa.us>
To: David G. Johnston <david.g.johnston@gmail.com>
Cc: tushar <tushar.ahuja@enterprisedb.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: pg_upgrade failed if view contain natural left join condition
Date: Thu, 20 Jul 2017 12:14:06 -0400
Message-ID: <4181.1500567246@sss.pgh.pa.us> (raw)
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"David G. Johnston" <david.g.johnston@gmail.com> writes:
> Per the docs:
> "If there are no common column names, NATURAL behaves like CROSS JOIN."
> I'm being a bit pedantic here but since NATURAL is a replacement for
> "ON/USING" it would seem more consistent to describe it, when no matching
> columns are found, as "behaves like specifying ON TRUE" instead.
Yeah, the analogy to CROSS JOIN falls down if it's an outer join.
I'll go fix that.
> I find it a bit strange, though not surprising, that it doesn't devolve to
> "ON FALSE".
No, it's normal that an AND of no conditions degenerates to TRUE.
It's like omitting a WHERE clause.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, david.g.johnston@gmail.com, tushar.ahuja@enterprisedb.com
Subject: Re: pg_upgrade failed if view contain natural left join condition
In-Reply-To: <4181.1500567246@sss.pgh.pa.us>
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