Hotsos Symposium Speaker – Henry Poras
Mr. Poras is a new Hotsos Symposium presenter.
Biography
Henry Poras has been an Oracle DBA for over ten years, working with custom applications as well as off-the-shelf products. He is currently developing an airline reservation system, which has strict HA and performance demands. Innovative techniques are being brought to bear in order to test this system prior to completion of development.
He has also developed and taught college courses for five years.
Presentation Title
Queueing Theory Analysis of Statspack Reports Obtained from Database Load Tests
Abstract
Queueing theory can help us extract much useful information from Statspack reports during database load tests. Applying these techniques to data obtained over varying loads allows us to determine the optimal load on the system. Additionally, we can model our system to help us validate our expectations ("Hey, our throughput isn't doubling as we double our user count...Well, should it? Really?" "Ummm, I don't know, why not?") and data (is our load test really testing what we think it should be testing?). We will also be able to confirm the source of resource bottlenecks, behavior of response time with load, and behavior of throughput with load.
In order to do all this, there are a number of assumptions which need to be made and tested in mapping between standard queueing theory parameters and Statspack data.
- Can the entire database be modeled as a queueing center? How is this different from breaking down the database into CPU and IO components?
- What is meant by sleep time (Z)? Sleep time for the application user or sleep time for the database (SQL*Net message from client waits)?
- Is N, the number of users, the number of application users? the number of database sessions (one user might spawn multiple sessions), the number of active sessions (what if most sessions in a session pool are inactive?)
- how do we measure throughput? PIO/sec? txn/sec? and how does this choice influence our interpretations?
Previous knowledge of queueing theory is not necessary.
Presentation Materials
Presentation materials are available to attendees only.
Schedule
The speaker schedule can be found at the following links:
