Method R Discussion GroupMethod R helps developers, DBAs, and decision-makers optimize Oracle-based software in every phase of the software life cycle. |
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Discuss Method R products, techniques, and events. Ask new questions or post your own responses. |
Why is Oracle scanning many blocks to get few rows? What does this indicate?
Two different questions. The first one could be caused by forgetting to put some filter or join conditions in the SQL, by having unrepresentative schema statistics, ... There are probably many other reasons as well.
The most common reasons for CBO estimates to be off is the unrepresentative schema statistics problem. But again, it could also be any number of other things as well. This sounds like a good problem to engage our consulting or education departments to help with. |
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