Query optimization and post-processing

Oracle makes certain assumptions about the capabilities of the ODBC driver referenced by DG4ODBC. Not everything can be influenced by configuration. As a result, queries that work well in other environments may show low performance or even timeout in Oracle. This is usually due to the fact that Oracle performs post-processing on certain query conditions, meaning it retrieves more data and applies remaining filter conditions locally.

This section helps you to understand what is going on in the background and explains how to avoid post-processing.