Articles & Content


Why did the optimizer choose that path? (Part 2 of 2) (A15)

Topic: DB2 for z/OS

Subtopic: 2006

DATE: 2006-10-5 (10:30 - 11:30)
SPEAKERS: Terry Purcell (IBM Silicon Valley Lab)

Ever wondered why the DB2 optimizer chooses a certain access path? The wrong index, poor table join sequence? In the DW world, this can cause a query to run for hours. This presentation will outline a method to utilize the extensive access path detail available with V8 Visual Explain and compare with the actual reality for a given query.

EXP. LEVEL: Beginner,Intermediate,Advanced


Query problems

Query breakdown

Comparing estimates with reality

What to do if the estimate is incorrect?

Automating the process

Click Here to Download

NOTE: These are only open to members of IDUG. If you are not a member, please CLICK HERE for more information.