Re: Myth of the database independent applications (Was: Are you using PL/SQL)

On Fri, 25 May 2007 10:33:38 -0700, zigzagdna wrote:

> Performance is very complex subject with so many variables, In many of
> our projets there were a few people assigned to do performance
> measueremts on frequenetly used transactions by users and batch
> processes.

Most present day DBA personnel is engaged in performance analysis, much more seriously then in the good, old days of BCHR and in helping developers. Being a DBA (Cary Milllsap's term is "performance analyst") my tuning philosophy always starts with the underlying application. There is very little that can be done to tune a bad query or to write a good query in a badly designed schema.
As for the measurements, the only relevant performance measurement is the response time. If the user community signs off on the application performance, then the performance is good and should not be investigated without somebody complaining. If the user community doesn't sign off on it, the application should be tuned until the response time is satisfactory. Anjo Kolk, Cary Millsap and Kirti Deshpande are people who usually get most credit for formulating the wait event/response time tuning manifesto.
There are many serious performance tuning techniques which involve the use of sophisticated tuning tools like Mercury LoadRunner and simulation of a realistic load, yet very few application vendors do that. Unfortunately, deals are usually not done this way. Software sales people are the only people that I trust less then used cars sales people or politicians. When a vendor wants to sell me a piece of "database independent software" I get extra cautious and ALWAYS ask for references in a similar configuration as the one they're trying to push. In my career, I eliminated many companies which were unable to provide such a reference. People using databases are not a monolithic market, people using SQL Server and MySQL are generally willing to pay much less then the people using Oracle or DB2. So called "database independence" is often just a pretense to grab the money and run. It is my job to ask questions like "do you feel lucky".

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http://www.mladen-gogala.com