Databasen - Revisited
abuse at cabal.org.uk
Wed Oct 18 18:08:26 BST 2006
On Wed, Oct 18, 2006 at 12:16:00PM -0400, Matt Sergeant wrote:
> There are lots of fairly obvious right answers (localisation would be one
> obvious one), but most people won't get the fact that the primary key
> index is a bad thing, because the entire table fits into a single page of
> pretty much every DB I know, so index access is actually slower than a
> full table scan.
I think I'd be wary of working for somebody who insisted this was actually
better and considered this sort of hack a virtue.
Any RDBMS worth its salt will skip the index if it's clearly faster to do a
full table scan. So all you've actually achieved is a less robust schema
which may, ironically, cause the optimiser to make poorer decisions.
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