On Wed, 2006-02-15 at 16:51 -0500, Tom Lane wrote:
> Gary Doades <gpd@gpdnet.co.uk> writes:
> > Interestingly, if I don't delete the table after a run, but just drop
> > and re-create the index repeatedly it stays a pretty consistent time,
> > either repeatedly good or repeatedly bad!
>
> This is consistent with the theory of a data-dependent performance
> problem in qsort. If you don't generate a fresh set of random test
> data, then you get repeatable runtimes. With a new set of test data,
> you might or might not hit the not-so-sweet-spot that we seem to have
> detected.
Agreed. Good analysis...
Best Regards, Simon Riggs