performance of Indexes in Composite key

[jmodic]

Originally posted by avi kumar
Now my First question is which query will give me the better performance weather index created by composite primary key will work?

Both will result in the same execution plan, hence the same performance in both cases. Composit index will (or will not) be used in botrh cases if optimizer chooses so. Nothing is preventing the usage of composite index in both cases, though.

Second Question is if i take single any field in where condition like :
"where f3='some value' "
then the index created by composite primary key will work or not

Generaly, in this case the composite index can not be used unless f3 is the leading column of the index.

However in 9i cost based optimizer might choose to use your composite index even if f3 is not the leading column of the index.