A query to help identify queries that need some tuning.  Read more...

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Occasionally in forums and on client sites I see conditional subqueries in statements. This is where the developer has decided...  Read more...

Following on from the previous TSQL performance tuning article in this series, we now focus on the important topic of T-SQL “Not IN” And “Not Exists “  Read more...

A UDF is very convenient for centralising business logic as we can specify a set of business logic in one UDF which references multiple stored procedures and ad-hoc queries. However, they can lead to significant performance degradation due to their demands on the CPU  Read more...

Reports stats on what the query optimizer records in the DMVs as missing indexes and what it says the cost savings will be if they were present. Can limit by table / schema name patterns.  Read more...

Reports index stats, index size+rows, member seek + include columns as two comma separated output columns, and index usage stats for one or more tables and/or schemas.  Read more...

This article will demonstrate a method of creating an Excel-based CPU/scheduler performance dashboard for SQL Server 2005+.  Read more...

Use your own optimizer to tune queries  Read more...

The short answer is, of course, none of them, but testing is the only way to be sure. I was asked,...  Read more...

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The arrival of the (MAX) data types in SQL Server 2005 were one of the most popular feature for the database developer. At the time, there was a lot of discussion as to whether this freedom from having to specify string length came at a cost. Rob attempts to give a final answer as to any down-side.  Read more...

Don't blame SQL Server if your SQL Statements perform badly! But where do you start to investigate the problem? This article is a primer on were to start looking when your SQL runs slowly.  Read more...

I’ve been working with execution plans quite a lot in SQL Server 2012. There are a number of changes, most of them associated with new or different functionality. I had not noticed anything really fundamental until recently. I’ve become a huge proponent of always checking the properties of the SELECT statement. There’s so much useful information in there about what’s happened with the plan generation in the optimizer (not low level stuff, but the big picture items) that you should always be checking it first as a fundamental part of your plan examinations.  Read more...

This artcle attempts to differentiate between the uses of WITH RECOMPILE and OPTION (RECOMPILE) features.  Read more...

When I read various forums about SQL Server, I frequently see questions from deeply mystified posters. They have identified a slow query or stored procedure in their application. They cull the SQL batch from the application and run it in SQL Server Management Studio (SSMS) to analyse it, only to find that the response is instantaneous. At this point they are inclined to think that SQL Server is all about magic. A similar mystery is when a developer has extracted a query in his stored procedure to run it stand-alone only to find that it runs much faster – or much slower – than inside the procedure.  Read more...

I heard this one over at SSC a while back. “Avoid IF statements in stored procedures as they result in...  Read more...

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Don't blame SQL Server if your SQL Statements perform badly! But where do you start to investigate the problem? This article is a primer on were to start looking when your SQL runs slowly.  Read more...

An article from Scott Zurolo tests the terformance of SQL Server 2008 Table Valued Parameters against more traditional methods of updating many rows at once.  Read more...