Db2 for LUW
John Hornibrook, IBM Canada
Optimal query access plans are essential for good data server performance and it is the query optimizer's job to choose the best one. However, occasionally no amount of statistics or tuning is enough to get the access plan you want. Or your application is effectively down, due to a poorly-performing query, and there isn't time to implement best practices. When these situations arise, Db2 optimization profiles and guidelines can be used to correct the access plan and get your application performing well again very quickly. Optimization profiles can specify various aspects of an access plan, control automatic query rewriting, or control the optimizer's plan search space. Guidelines can be specified with or without modifying your application. This presentation will show you what options are available and how to use them effectively.