On Sun, 2006-12-10 at 14:57 -0500, Tom Lane wrote:
> Comments in general? I'm a bit worried that these changes will bias
> us
> against indexscans too much, but there's no sign of that in Arjen's
> results.
Are Arjen's tests on prepared queries? Does that change anything? We shy
away from indexes on prepared queries too much already, important when
the consequence of doing so is an O(N) seqscan rather than an O(logN)
indexscan.
The cost of initiating an index scan is a cause for concern, but it
seems reasonable to get it accurate. I'd like to perform some of that
work at planning time, not at scan time, when it is possible for us to
do so. Simple indexed, planned queries shouldn't need to pay that cost
repeatedly.
--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com