On Fri, 9 Jan 2004, Richard Huxton wrote:
> > > select invheadref, invprodref, sum(units)
> > > from invtran
> > > group by invheadref, invprodref
>
> > For the above query, shouldn't you have one index for both columns
> > (invheadref, invprodref). Then it should not need to sort at all to do the
> > grouping and it should all be fast.
>
> Not sure if that would make a difference here, since the whole table is being
> read.
The goal was to avoid the sorting which should not be needed with that
index (I hope). So I still think that it would help in this case.
--
/Dennis Björklund