SQL Server Performance Tuning

When I run a stored procedure in Query Analyzer, it runs in about two minutes. But if I execute the same stored procedure as a job, it runs several hours.

Question When I run a particular stored procedure in Query Analyzer, it runs in about two minutes.  But if I execute the same stored procedure as a scheduled job, it runs several hours before it completes. What could be the obvious reasons for this? AnswerWhen I first got this question, I didn’t have an answer. […]

We have five SQL servers running on different physical servers. What are the downfalls for combining these SQL servers onto a single physical server?

Question We have five SQL servers running on five different physical servers. What are the downfalls for combining these SQL servers together onto a single physical server? Also, is it possible to run multiple instances of SQL Server on the same server? Answer The answer to this question depends on if the single physical server has […]

Is it a good idea to run both SQL Server and IIS on the same physical server?

Like so many questions, the answer to this question is “it depends.” For ideal performance, and assuming your have a big enough budget, you should put SQL Server and IIS on their own dedicated servers (properly sized). But if you don’t have the budget for two servers, then one will have to suffice, at least […]

I need help to justify new hardware for our SQL Server.

Question I am a new DBA in my company. My department needs a new server to run SQL Server and we must make a proposal to our owner in order to justify the cost of replacing the old server. I have read every article on your web site, but I still don’t know how to […]

How can I help identify the worst performing queries in my SQL Server database application?

This is an easy task using the SQL Server Profiler. Create a new trace in Profiler using the following configuration: Select These Event Classes SQL:BatchCompleted Select These Data Columns Groups Duration Columns EventClass TextData CPU Application Name LoginName NTUserName SPID Select These Filters (as needed) Application Name DatabaseName Duration As the above trace runs, you […]

We have two stored procedures taking five minutes to run in our development database, but the same stored procedures run quickly on our QA database. Why?

Question We have two stored procedures taking about five minutes to run in our development database. The same two stored procedures run quickly on our QA database. Both databases are on the same physical server. What can account for this difference? Answer There are several possibilities: The data is different, which can lead the query […]

When I upgraded by database to the newest version, performance is now much slower. Why?

Most likely, you need to update the statistics of all the indexes in your new SQL Server database. The easiest way to do this is to create a database maintenance plan and select the “Update statistics used by query optimizer” from the “Update Data Optimization Information” screen of the maintenance wizard, then run it now, […]

Our query used to take 30 seconds, and now it takes over 30 minutes. Why?

Question We have a SQL Server stored procedure that normally runs in less than 30 seconds. It has been running fine for over 6 months. But today, at about 11:00 AM, it started to take over 30 minutes to run. I took a Profiler trace of the stored procedure when it ran, and it performed […]

When should primary keys be used?

Question Our department is fairly new to SQL Server. I apologize if these are dumb questions, but I’ve spent hours digging on the Internet and cannot find answers to my questions. When we create our tables, we create a clustered unique index on the column(s) that best fits the table and the way it will […]

Can I programatically tell SQL Server how to allocate CPU resources?

Question My SQL Server is running on a dual processor box. What I would like to do is to use one of the CPUs for background tasks, and the other processor for online tasks. And if there are no background tasks running, I would like both processors to serve online tasks. How can I do […]
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