Cardinality feedback tuning

Wolfgang Breitling has proposed cardinality feedback tuning method and it works very well for Oracle.
I have to agree with him that it would be nice if Oracle can automatically apply this method. Whenever the optimizer sees an intermediate cardinality to be drastically different than the query plan as defined below, it should retry with a different plan that produces such a cardinality or close:
1. 0 to non-0, or vice versa.
2. 1 to 1+, or vice versa.
3. n to 100n, (or a threshold that can be set by user), or vice versa.

I don’t see it in 11g though, but that will be the ultimate feature and perhaps the end of Oracle performance tuning consultancy.


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