optimizer

From: Hemei <Hemei_at_yahoo.com>
Date: Tue, 1 Jun 1999 21:18:21 -0400
Message-ID: <7j77bg$2hn$3@news.udel.edu>

I want to user oracle optimizer to tune my query. Here I have some questions and need your help.
a.when I execute a query, I get the following message Execution Plan

0 SELECT STATEMENT Optimizer=CHOOSE (Cost=33 Card=1) 1 0 SORT (AGGREGATE)
2 1 TABLE ACCESS (FULL) OF 'BP_OPTION' (Cost=33 Card=2299) Could you tell me what the '(cost=33 card=1)' means?

b.If I execute another query to do the same thing and get a different execute plan, how do I know which query is better?

c.when I execute a similar query on different table, say 'select count(1) from table_name', the cost values I get are different. Couls you tell me what elements may affect the cost value?

Thanks.

Peng Nie
peng.nie_at_mortgagefamily.com Received on Tue Jun 01 1999 - 20:18:21 CDT