Tuning of SQL queries requires understanding why DB2 chose a particular access path and determining whether or not that access path should perform as expected. The key to this is understanding what filter factors are, how they are used by the Optimizer and how to get DB2 to better estimate them,
Let’s start this discussion candidly – I am a big fan of the FETCH FIRST n ROWS ONLY clause coded in a SQL statement. That assertion will require some clarification, since there are some valid use cases, and others that make little sense. Regardless, I will try not to over-complicate the discussion.
In this article we are going to examine some tuning options that a DBA has available to help improve dynamic SQL performance on DB2 LUW.
IBM® Data Server Manager is an integrated database management tools platform. In this article, learn how to use the Query Tuning functionality that is included with the Base edition of DSM at no additional charge to tune the queries running in your DB2® for z/OS® environment.
Performance problems can be tough to solve, especially if you've not had to deal with them much before. In this session from IDUG NA 2016, Steve Rees goes through a step-by-step, decision tree-based approach for tackling performance problems.