From: | Bruno Wolff III <bruno(at)wolff(dot)to> |
---|---|
To: | Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net> |
Cc: | PgSQL General ML <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Grouping by date range |
Date: | 2003-08-20 19:16:17 |
Message-ID: | 20030820191617.GA30279@wolff.to |
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Thread: | |
Lists: | pgsql-general |
On Wed, Aug 20, 2003 at 14:02:59 -0500,
Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net> wrote:
> On Wed, 2003-08-20 at 13:58, Bruno Wolff III wrote:
> > On Wed, Aug 20, 2003 at 13:44:59 -0500,
> > Ron Johnson <ron(dot)l(dot)johnson(at)cox(dot)net> wrote:
> > >
> > > The GROUP BY does implicit sorting, so an ORDER BY on the exact same
> > > column(s) as the GROUP BY is redundant.
> >
> > That is an implementation detail, not a promise. With hashed aggregates
> > in 7.4, you might find this isn't true.
>
> Now that's interesting. I'd have gone to my grave thinking it was
> part of the spec...
I just tried something out quick and a select with group by didn't
return the data in ascending order. (This is on CVS from about a week ago.)
bruno=> create table temp (col int);
CREATE TABLE
bruno=> insert into table values (3);
ERROR: syntax error at or near "table" at character 13
bruno=> insert into temp values (3);
INSERT 182888 1
bruno=> insert into temp values (1);
INSERT 182889 1
bruno=> insert into temp values (2);
INSERT 182890 1
bruno=> analyze temp;
ANALYZE
bruno=> select * from temp group by col;
col
-----
3
2
1
(3 rows)
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