Jonathan Lewis - Interpreting Parallel Execution Plans "Late Show" - 2:00 PM US EDT 20:00 CEST
Tuesday, April 15, 2014 from 2:00 PM to 3:30 PM (EDT)
San Francisco, California
London, United Kingdom
Interpreting Parallel Execution Plans
When you read an execution plan you’re probably trying to identify the steps that Oracle went through to acquire the final result set so that you can decide whether or not there is a more efficient way of getting the same result.
For a serial execution plan this typically means you have to identify the join order, join methods and access methods together with the point at which each predicate was applied. Generally this isn’t too difficult although there are a few cases where the difference between join order and the order of operation can be slightly obscured.
Parallel execution plans are harder, though, because you really need to understand the impact of the order of operation, distribution mechanisms chosen, and (in recent versions of Oracle) the timing of the generation and use of Bloom filters.
In this presentation we examine the basics of how parallel execution slave work, and the way in which this can result in a massive difference between the join order of an execution plan and the order of operation of the steps of that plan. We learn about “table queues” and how they help us follow the order of operation, and how the distribution method can make a dramatic difference to performance – following which we then learn how to use hints to optimise parallel queries.
Speak-Tech is Minnesota-based and has organized webinars and seminars featuring the world’s leading Oracle experts for over 12 years.
Speak-Tech has organized over 100 training events for experts such as Jonathan Lewis, Tom Kyte, Cary Millsap, Tim Gorman, Gaja Krishna Vaidyanatha and David Kurtz, considered to be some of the world’s leading experts in Oracle Performance Tuning; Syed Jaffar Hussain, Oracle ACE Director who was awarded the Oracle Excellence Award for Technologist of the Year: DBA, 2011; Steven Feuerstein, considered to the world's leading expert in PL/SQL, Jim Czuprysnski and Matt Hart, all leading experts in their Oracle specialties.