Re: [HACKERS] No: implied sort with group by

> > > postgres=> select b,c,sum(a) from t1 group by b,c;
> > > b|c|sum
> > > -+-+---
> > > |x| 5
> > > |z| 3
> > > |x| 0
> > > (3 rows)
> > >
> > > postgres=> select * from t1;
> > > a|b|c
> > > -+-+-
> > > 1| |x
> > > 2| |x
> > > 2| |x
> > > 3| |z
> > > 0| |x
> > > (5 rows)
> > >
> > > I just inserted a single out-of-order row at the end of the table which, since the
> > > integer value is zero, should have not affected the result. Sorry I didn't understand
> > > the nature of the test case.
>
> > Hmmm...is this a grouping problem or an aggregate problem? Or both? The first
> > query above should have the data sorted before aggregating, shouldn't it, or I
> > am still missing a piece of this puzzle?
>
> fwiw, I see the same incorrect behavior in v6.2.1p5.
>
> - Tom
>
>
And in v6.1. If b is a space (rather than a NULL), then the behaviour is correct
so it must be a problem in grouping NULLs.

Andrew

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Dr. Andrew C.R. Martin University College London
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