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SQL PASS Summit 2009

DBA-437 – The Problem With Parallelism

The SQL PASS Summit for 2009 saw over 2,100 attendees.

I was particularly impressed with the breadth and depth of the presentations on offer. I am very much looking forward to going through all the sessions on the DVDs when they are released.

Thank you very much to the gentleman at the back of my session who asked about worker threads. As I indicated, the defaults are fairly well documented in SQL Server BOL:

The default value for max worker threads, 0, allows SQL Server to automatically configure the number of worker threads at startup. This setting is best for most systems; however, depending on your system configuration, setting max worker threads to a specific value sometimes improves performance.

The following table shows the automatically configured number of max worker threads for various combinations of CPUs and versions of SQL Server.

Number of CPUs

32-bit Computer

64-bit Computer

<= 4 processors



8 processors



16 processors



32 processors



 Note: We recommend 1024 as the maximum for 32-bit SQL Server and 2048 for 64-bit SQL Server.

Importantly, don’t forget that earlier version of SQL Server defaulted to 255 for the max worker threads configuration option. So if you perform/performed an in-place upgrade on your SQL Server 2000 instance you should ensure that the value be changed to 0 for SQL Server 2005 and 2008.

I have included my presentation below:


Otherwise, it was great to catch up with the "usual punters" at the "local office", the Tap House Grill. The seasonals were great!
See you next year!


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