Re: [HACKERS] INTERSECT/EXCEPT and duplicates?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: t-ishii(at)sra(dot)co(dot)jp
Cc: pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] INTERSECT/EXCEPT and duplicates?
Date: 1999-08-05 14:09:37
Message-ID: 4014.933862177@sss.pgh.pa.us
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Tatsuo Ishii <t-ishii(at)sra(dot)co(dot)jp> writes:
> SQL92 seems to assume that results of the INTERSECT/EXCEPT contain no
> duplications unless "ALL" is specified. However PostgreSQL 6.5.1 does
> not follow the requirement, I think.

I think you are right --- the ALL keyword is only implemented for UNION
(and it's not quite right there either :-(). For the other two, you
just get whichever behavior was easiest to implement, I suppose...

regards, tom lane

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