Re: EXPLAIN PLAN

Kevin Woolley (kjw1_at_stir.ac.uk) wrote:

: It's generally easier to use cost based optimization, to do this you
: need to generate statistics on your tables and indexes (and clusters if
: you have any) using the ANALYSE statement. In practice estimate
: statistics seems to work indistinguishably from calculate and is a hell
: of a lot faster.

A couple of related questions, one of which I raised in an earlier posting:

What percentage do you use when you run ANALYZE with the ESTIMATE option? So far I've only gotten one response to that question. Larger samples do seem to improve performance, but there must be a point of diminishing returns.

Second, the manual is clear that when you say ANALYZE TABLE, Oracle automatically analyzes the indexes too. I'm relying on that; should I?

--
Tad Davis                  215-898-7864 voice
(davist_at_isc.upenn.edu)     215-898-0386 fax