SQE and CQE engines
It is important to understand the implementation differences of query management and processing in CQE versus SQE.
The following figure shows an overview of the IBM®
Db2® for i architecture. It shows the delineation between CQE
and SQE, how query processing is directed by the query dispatcher, and where each SQE component
fits. The functional separation of each SQE component is clearly evident. This division of
responsibility enables IBM to more easily deliver functional
enhancements to the individual components of SQE, as and when required. Notice that most of the SQE
Optimizer components are implemented below the MI. This implementation translates into enhanced
performance efficiency.
As seen in the previous graphic, the query runs from any query interface to the optimizer and the query dispatcher. The query dispatcher determines whether the query is implemented with CQE or SQE.