>
> And they are in appropriate ... when?
- When they hide important information from the CBO:
* low distinct cardinality columns with uneven distribution of the
frequencies.
In such cases, you create histograms and, ideally, use literals in
predicates. That's somehow addressed by Oracle since 9.0.2 with the
bind variable peeking feature, but still... it only has an effect on
the hard parse, since binding a different value does not invalidate
the parsed cursor (that's the whole point...)
- when using list or range partitioning
Using literals allows the CBO to prune partitions at parse time,
rather than at execute time
Cheers,
Flado
Received on Mon Dec 08 2003 - 06:18:47 CST
