Re: UNION DISTINCT in doc - Mailing list pgsql-hackers

From Hitoshi Harada
Subject Re: UNION DISTINCT in doc
Date
Msg-id AANLkTik=XKoPQvrQ+OJ_z9nhVj7kAXiVLYMsPcramMxz@mail.gmail.com
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In response to Re: UNION DISTINCT in doc  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: UNION DISTINCT in doc
List pgsql-hackers
2010/10/15 Tom Lane <tgl@sss.pgh.pa.us>:
> Hitoshi Harada <umi.tanuki@gmail.com> writes:
>> UNION DISTINCT is nothing more than UNION itself, but gram.y
>> definitely accept it and the SQL standard describes it as well. Should
>> we add DISTINCT to docs?
>
> I think it'd be hard to describe without confusing people, because
> while DISTINCT is a noise word there, it's definitely not a noise
> word after SELECT.  And the way that the reference pages are laid
> out, it's hard to connect different descriptions of the same
> keyword to different usages.  If you can think of a non-forced
> way of describing this, fine.  But I don't have a problem with
> leaving it as an undocumented standards-compliance nit.

I thought adding DISTINCT next to ALL is enough like

select_statement UNION [ ALL | DISTINCT ] select_statement

and say "UNION DISTINCT is identical to UNION only" or something. That
sounds not so confusing with DISTINCT clause description.

Regards,

--
Hitoshi Harada


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