Understanding Query Transformation in DB2 for z/OS

Tuesday, 27 May, 2014 - 15:00 - 16:00
z/OS Track
Daniel Luksetich

There is always a lot of talk about the DB2 optimizer and what is the best access path for a particular query. While this is of course important it is also important to know that the optimizer is only part of the story. When a query is submitted one of the first thing that happens is that it goes through query transformation. In this part of the process DB2 interprets the submitted SQL, and rewrites it. Views and UDFs are merged with the query, subqueries possibly transformed to joins, table expressions merged, and much more. If you are a serious query tuner you need to understand what is happening during query transformation and what you can do to influence it. We'll learn about query transformation, how to view query transformation, and how to influence query transformation



SQL Adria is the independent, non-profit organization that gathers relational database users for Croatia and Slovenia. It was founded 1994. and in the same year it has become the regional user group.

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