A customer needs to do a cross database join between two tables where, one of...

You can specify a Driving table parameter in a complex join.

Driving tables are for use in optimizing the manner in which the Oracle BI Server processes cross-database joins when one table is very small and the other table is very large.

The BI Server will query the driving table (the small one) and will get a list of values. The BI Server will then generate a second SQL using a parameterized IN list with the values from the first query.

Specifying driving tables leads to query optimization only when the number of rows being selected from the driving table is much smaller than the number of rows in the table to which it is being joined.