Presentation Title: Optimisation through Understanding
Speaker: Mr Jonathan Lewis
Company: JL Computer Consultancy
Co-presenter: 
Presentation abstract: Once you start to write complex SQL statements it's fairly common to see the optimizer making mistakes. In such cases, you need to review the data, understand what should happen, and force the relevant access path. But unless you know what can be done, and why it needs to be done, that's not an easy task.

In this presentation we examine a single SQL statement and show that the optimum execution path depends entirely on a good understanding of the data volumes, the data relationships, and the available indexes. In the course of the presentation we will see several different execution paths for that one statement. One is a path the optimizer will never find; one is a path a human being would (probably) never think of; each of the paths would be correct path for a specific set of circumstances.

After seeing this presentation, you will be better equipped to deal with the problems of analysing and optimising complex SQL.

Presentation begins: 06/12/2007 13:10
Presentation duration: 125
Presentation content level: 2 (1 = indepth, 5 = strategic overview)
Audience experience: Experienced (2-3 years)
Audience function: 
Speaker biography: Jonathan Lewis has nearly 20 years experience with Oracle databases, and is a well-known speaker in the UK (and international) Oracle community, and has picked up several awards for his contribution to the community. He is the author of two books, the most recent being "Cost Based Oracle - Fundamentals", the first volume of a planned trilogy that - like the Hitchhiker's Guide to the Galaxy - may end up as five volumes.
Related topics: Server Technology: Performance Tuning & Diagnostics, Server Technology: Other Server Technology & DBA Topics, Server Technology: General - Technology
Hall: 5