New tip published about table statistics

Published On: 2007-10-25By:

Upgrade for sp_who2 called sp_who3

Published On: 2007-10-24By:

I’ve published this before over on tek-tips.com, but I figured that I’d republish it here as well.  I’ve written an update for sp_who2 which I call sp_who3.  It can be most useful when trying to diagnose slow running queries as it can provide a wealth of information in a single screen.

Usage:
exec sp_who3
exec sp_who3 active
exec sp_who3 blocked
exec sp_who3 72 /*Any active spid*/

Download: SQL 7 / SQL 2000 / SQL 2005

Download from mrdenny.com

When using no parameter the output will match the output of sp_who2.

When using the “active” keyword the output will match the output of sp_who2 active.

When using the “blocked” keyword the output will have the same columns as sp_who3 active but show only the blocking and blocked processes.

This procedure has been used at companies like IGN / GameSpy, MySpace, Awareness Technologies, and Triad Financial to name a few.

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How SQL decides how much procedure cache and how much buffer cache to use.

Published On: 2007-10-22By:

There are two main types of cache which SQL Server deals with, the buffer cache and the procedure cache.  The procedure cache is where the execution plans for procedures and queries are stored.  The buffer cache is where the actual data is cached so that SQL Server doesn’t have to go to disk to get often accessed data.

The version of SQL Server that you are running will determine how SQL calculates the maximum size of the procedure cache.

SQL 2000 – 50% of the memory or 1 Gig which ever is lower

SQL 2005 RTM to SP1 – 75% of the first 8 Gigs of RAM + 50% of the next 56 Gigs of RAM + 25% of the ram over 64 Gigs.

SQL 2005 SP2 and up – 75% of the first 4 Gigs of RAM + 10% of the ram over 4 Gigs

As I understand the reason for the change the original settings were causing SQL Server to lockup for some customers as not enough RAM was left over for the buffer cache.

If you are using SQL 2005 in a Win32 platform these calculations change again as the procedure cache must remain within the first 2 Gigs of memory giving you a max of 2 Gigs of procedure cache no matter how much memory you install.

Denny

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Excellent Lock Pages in Memory Blog

Published On: 2007-10-18By:
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