Query design for performance with DB2 Multisystem

You can design queries based on these guidelines. In this way, you can use query resources more efficiently when you run queries that use distributed files.

This topic also discusses how queries that use distributed files are implemented. This information can be used to tune queries so that they run more efficiently in a distributed environment.

Distributed files can be queried using SQL, the Open Query File (OPNQRYF) command, or any query interface on the system. The queries can be single file queries or join queries. You can use a combination of distributed and local files in a join.

This topic assumes that you are familiar with running and optimizing queries in a nondistributed environment. If you want more information about these topics:

• SQL users need to refer to the SQL reference and SQL programming concepts information.
• Non-SQL users need to refer to the database programming and control language information.

This topic also shows you how to improve the performance of distributed queries by exploiting parallelism and minimizing data movement.