On Friday 09 January 2004 08:57, Dennis Björklund wrote: > 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.
Sorry - not being clear. I can see how it _might_ help, but will the planner take into account the fact that even though: index-cost > seqscan-cost that (index-cost + no-sorting) < (seqscan-cost + sort-cost) assuming of course, that the costs turn out that way. -- Richard Huxton Archonet Ltd ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly