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Re: Intersection or zero-column queries - Mailing list pgsql-general

From Victor Yegorov
Subject Re: Intersection or zero-column queries
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Msg-id CAGnEbohAYxEXt86+Wi84+dOaPZU=bPfk6wNg6zutt3=fntmskg@mail.gmail.com
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In response to Re: Intersection or zero-column queries  ("David G. Johnston" <david.g.johnston@gmail.com>)
Responses Re: Intersection or zero-column queries
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2017-12-22 2:03 GMT+02:00 David G. Johnston <david.g.johnston@gmail.com>:
On Thu, Dec 21, 2017 at 4:53 PM, Victor Yegorov <vyegorov@gmail.com> wrote:
    postgres=# select except select;
    --
    (2 rows)
    postgres=# select intersect all select;
    --
    (2 rows)

Why is it so?
Should this be reported as a bug?.. ;)

​The intersection case seems correct - one row from each sub-relation is returned since ALL is specified and both results as the same.

Actually, result will not change with or without `ALL` for both, EXCEPT and INTERSECT.

Also, intersection should not return more rows, than there're in the sub-relations.


--
Victor Yegorov

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