Chapter 2. The architecture of DB2 for i5/OS 13
2.2 Query processing before OS/400 V5R2
To fully understand the implementation of query management and processing in DB2 for
i5/OS starting with OS/400 V5R2, it is important to see how the queries were implemented in
previous releases of OS/400 for DB2 Universal Database for iSeries.
Figure 2-1 shows a high-level overview of the architecture of DB2 Universal Database for
iSeries before OS/400 V5R2. The optimizer and database engine are implemented at
different layers of the operating system. The interaction between the optimizer and the
database engine occurs across the Machine Interface (MI). This results in a definite
performance overhead. This is one of the areas that was targeted for improvement during the
re-engineering process of DB2 Universal Database for iSeries for OS/400 V5R2.
Figure 2-1 Database architecture before OS/400 V5R2
2.3 Query processing starting with OS/400 V5R2
There are several new and updated components of SQE starting from OS/400 V5R2. The
SQE components include:
SQE Data Access Primitives
In the following section, we look briefly at the underlying architecture that supports SQE in
OS/400 starting with V5R2. We follow this with a detailed discussion of the SQE components.
Machine Interface (MI)
DB2 Universal Database
(Data Storage and Management)
Prepare once and