CBO choose full table scan, not index
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From: lsllcm on 28 Nov 2007 01:26 Thank you, I will do more read on it, But using index is faster than full table scan, but the cost of index is high full table scan.
From: DA Morgan on 28 Nov 2007 02:18
lsllcm wrote: > Thank you, I will do more read on it, > > But using index is faster than full table scan, but the cost of index > is high full table scan. Full table scans can be faster and more efficient than using an index. Which is better in a specific situation changes depending on many factors. It is also important to remember that an EXPLAIN PLAN is the CBO guessing at what it will do: It is not the actual SQL PLAN used. The only thing that matters is what Oracle actually does and that is why we have 10053 traces. -- Daniel A. Morgan Oracle Ace Director & Instructor University of Washington damorgan(a)x.washington.edu (replace x with u to respond) Puget Sound Oracle Users Group www.psoug.org |