From a performance perspective, because the Oracle ADF Model Layer does not support aggregation, such queries tend to be slow (aggregations performed on low-level data in Oracle BI EE). Going through additional servers (JavaHost plus Oracle ADF) in the network is slower than directly querying the database. The related SQL Bypass feature directly queries the database and pushes down aggregations and other transformations where possible, reducing the amount of data streamed and worked on in Oracle BI EE.
The SQL Bypass functionality in Oracle BI EE uses the Composite view object API feature to construct and return a flattened SQL Bypass query that incorporates all (and no more) of the required columns, filters, and joins required by the BI query. Oracle BI EE then executes this query directly against the database.