RE: high cpu on query
- From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
- To: <joseph.armstrong-champ@xxxxxxxxx>, "ORACLE-L" <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 29 Jun 2007 11:34:56 -0700
I'm too busy to even read your whole situation in depth (in the middle
of a restore), but in general, high cpu use is usually a sign of a lot
of buffer gets, which is usually a sign of indexes and nested loops
being used where perhaps a full table scan and hash join or sort-merge
join would be more appropriate. This is a typical problem I see when
explain plans are shared inappropriately due to bind variable peeking -
search Metalink for "query using bind variables is suddenly slow" for
more info - I don't have the note number on hand. Good chance you got a
plan using "MERGE JOIN - CARTESIAN" with a "BUFFER SORT" because the
plan was optimized based on estimated cardinality of 1 with the peeked
bind variables, then later the same query was executed with different
bind variables selecting much more than 1 row.
Regards,
Brandon
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