database performance, sql tuning and data visualization
Wednesday, May 5, 2010
Jonathan Lewis and Visual SQL Tuning
Sometimes, it is a great idea to push away the keyboard when tackling the problems of an ill-performing, complex, query, and take up pencil and paper instead. By drawing a diagram to show off all the tables involved, the joins, the volume of data involved, and the indexes, you'll see more easily the relative efficiency of the possible paths that your query could take through the tables.
-- Jonathan Lewis
Check out Jonathan's insightful article on the power of graphically representing a SQL statement to help identify efficiencies and inefficiencies in a SQL query:
Before working at Embarcadero I redesigned the performance pages in Oracles OEM 10g (see a before and after example). I am on the patent from the team for our tuning methodology (Patents: 20060059205) . I freely provide graphical monitoring tools such as ASHMON (TCL/TK) as well as scripts to profile database load such as S-ASH ie Simulated ASH (PLSQL). S-ASH, ASHMON and more are available at my old site http://ashmasters.com/ . I have made available C code to directly read profiling data out of Oracle's memory structures, called Direct Memory Access. I speak at conferences and give classes around the world.This blog has some of my new ideas on Visual SQL Tuning (VST), work on DB Optimizer, possibly some past material on DB performance monitoring as well as lots of references and pointers to other information on the web that I find important and worth emphasizing.