On Fri, May 30, 2003 at 10:57:33 +0200,
SZUCS Gábor <surrano@mailbox.hu> wrote:
> Nikolaus,
>
> I think that shouldn't be any more effective. As I experienced, it's
> irrelevant how many cols an index has as long as you only use the first
> column. And, after that, if you use another column, how could a missing
> second column be any better?
Because the index will be more compact and reside on less disk blocks.
The planner also makes different guesses for the selectivity whne using
the first column of a multicolumn index as opposed to a single column
index.