To use full pushdown optimization, the source and target databases must be in the same relational database management system. When you run a session configured for full pushdown optimization, the Integration Service analyzes the mapping from the source to the target or until it reaches a downstream transformation it cannot push to the target database. It generates and executes SQL statements against the source or target based on the transformation logic it can push to the database.
When you run a session with large quantities of data and full pushdown optimization, the database server must run a long transaction. Consider the following database performance issues when you generate a long transaction:
A long transaction uses more database resources.
A long transaction locks the database for longer periods of time. This reduces database concurrency and increases the likelihood of deadlock.
A long transaction increases the likelihood of an unexpected event.
To minimize database performance issues for long transactions, consider using source-side or target-side pushdown optimization.