Antares is right about how it'll go about executing. If you don't mark it as a system stored procedure, it will get around to executing the one in the local database. However, you will take a performance hit. Here's why...

SQL Server will initially look for the execution plan in the master database. This will result in a cache miss event. SQL Server will then put an exclusive [COMPILE] lock on said stored procedure. Exclusive means exclusive... only one process can use it as a time. SQL Server will then do a second, more comprehensive search to match up the stored procedure with an execution plan. It it finds it (and it should after you've run it once), it will then register an ExecContextHit and attempt to reuse the cached execution plan. Only then will it release that [COMPILE] lock.

This will happen every time the stored procedure is executed. Meaning if you've got several processes that could be calling the stored procedure, they will queue up. Remember, that even though one process has the stored procedure running and has released the [COMPILE] lock, the next process can't do anything until the first process is done. This is because the [COMPILE] lock is exclusive. As a result, you'll serialize the stored procedure where only one process can use it as a time.

HTH.

K. Brian Kelley

http://www.truthsolutions.com/

Author: Start to Finish Guide to SQL Server Performance Monitoring

http://www.netimpress.com/shop/product.asp?ProductID=NI-SQL1