OracleGuy

Emerging database technologies

At Collaborate 2008 I'm giving an updated version of my RDBMS industry and technology trends talk.  A lot of the new content has to do with "Cloud DB"s and C-Store and H-Store proposals.  I''m writing article on these technologies, there's an early draft of it here. 

Using _spin_count to reduce latch contention in 11g

Back in 2003, I published the results of experimenting with various values of _spin_count to improve throughput on latch congested systems. You can find the original paper here.

The study involved varying spin count on an Oracle 8.1.6 database suffering from heavy cache buffer chains latch contention.  The database was running on a Windows 2000 server.  The results of this study confirmed that _spin_count can be very effective in improving the throughput of latch contention-bound systems.  In the test, throughput almost doubled when spin_count was raised from the default of 2000 to 10000.

I recently repeated these tests for Oracle 11g.  This time, the database was experiencing shared pool and library cache latch contention and was running on RHEL 5.0.  The results will be published soon in my contention series at ToadWorld.   To summarize however,  increasing spin_count in 11g was equally effective in reducing latch contention.  As _spin_count increased, latch  waits reduced and throughput increased, up until CPU saturated, at which point no further improvements were achieved.

Accessing Oracle from Powershell

I've used perl extensively - and other scripting languages from time to time - to write little unitities or simulations for Oracle.  Perl is available on windows, but it doesn't provide easy access to all the Windows API and .NET utilities (such as accessing WMI counters).  For that PowerShell would be the best choice.

It's not entirely obvious how to connect to oracle from Powershell.  Here's how I did it.

Systematic Oracle Performance Tuning

When faced with an obviously IO-bound database, its tempting to deal with the most obvious (symptom)  the IO subsystem  immediately.  Unfortunately, this usually treats symptoms rather the cause, is often expensive and usually futile.  Here's my article on a more systematic approach:

Systematic Oracle tuning (pdf)

and here's the powerpoint from the recent NOCOUG conference.

Grid control therapy

I've had a lot of bad experiencing installing and managing the OEM grid control.  Today has been the worst day ever and - as an alternative to self-mutilation - I decided that I would document my woes as they occur as a sort of therapy

10g tracing quick start

Oracle’s released a few new facilities to help with tracing in 10g,  here’s a real quick wrap up of the most significant:

10g time model query

Joining the 10g time model to the traditional wait interface views and taking advantage of the wait_class data is something most of us have probably done.  Here's my standard queries that do that thing....