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Why did the optimizer choose that path? (Part 1 of 2) (G04)

Topic: 2006 NA

Subtopic: DB2 for z/OS



DATE: 2006-5-9 (08:30 AM - 09:40 AM)
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? Before DB2 V8, you had to be an optimizer expert to answer that question. 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

OBJECTIVES:

Query problems

Query breakdown

Comparing estimates with reality

What to do if the estimate is incorrect?

Automating the process



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