Average Active Sessions (AAS) Formulas, Interpreting Load Charts and Visual SQL Tuning (VST)
Kyle begins his presentation with a discussion of the use of sample data to create Active Sessions History (ASH). But ASH is dense, multidimensional data, which makes it difficult to analyze. Fortunately, ASH can be simplified using a metric called Average Active Sessions (AAS). AAS shows the load on the database and allows you to drill down with precision and clarity into the cause of each bottleneck.
Most often, bottlenecks are caused by poor-performing SQL statements. For analyzing suboptimal SQL statements, Kyle will show you how to lay out the query graphically in a Visual SQL Tuning (VST) diagram. Through the VST, you’ll learn how to quickly visualize any coding errors in the query, discover flaws in the underlying database schema, and most importantly, find the best execution path through the 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.