These days if you get a new server-class machine to run SQL Server, you can almost be 100% sure that it’ll be running on NUMA hardware. The recent AMD Opteron and Intel Nehalem-based processors are all built on some form of NUMA architecture. The current consensus is that as the number of processors grows, their shared memory bus can easily get ...

This is in part a response to a comment by Paul White (@SQL_Kiwi) to my previous post on the performance impact of enabling hyperthreading (HT) on OLTP queries, and in part due to my desire to capture a more complete set of test data for future investigation on this very topic. I’m posting below the results of re-running the same exact test as ...

My previous post focuses on the performance impact of enabling hyperthreading (HT) on a machine with four Intel Westmere-EX processors on reporting queries. Let’s turn our attention to OLTP queries. To oversimplify it, reporting queries are generally processed by scanning a large number of pages, whereas quick index seeks are the hallmark of OLTP ...

There are a lot of questions on hyperthreading, but not a lot of answers.  There is no shortage of opinions, but very few are based on significant first hand experience or solid test data. We know that the hyperthreading technology in the older generations of the Intel processors was not well received by the SQL Server community. ...

For nearly ten years, I have had success in using a specifically modified version of the TPC-C benchmark for evaluating server hardware running SQL Server. Depending on your purpose, you can evaluate computer hardware in numerous ways with numerous benchmarks. Arbitrarily picking a generic benchmark to evaluate a server is of no interest to me. ...

I do a lot of public speaking over the course of the year at many different conferences and events. I always try to carve out time during and after the presentation to take questions from the audience. While many of these questions are de riguer, I often get questions that can only be described as ''How do I handle this ... <insert IT horror ...

I’m running into this little performance tuning pattern enough number of times that it is worth a special mention. As it often happens, the app folks complain about a proc call being very slow, and I track it down to a specific line in the proc. The line appears to be harmlessly simple, as simple as the following: SELECT MAX(BusinessDate) FROM ...

In commenting on my previous post, Greg Linwood and GrumpyOldDBA raised questions about various implications of parallelism. In this post, I’ll look at the impact of different degrees of parallelism on the query performance. I’ll limit my examination on the same query that uses a Cartesian product temp table, as discussed in the previous two posts ...

Although Cartesian product as a concept is essential to the relational database theory, it is often a dirty phrase – something that is associated with bad performance and therefore should be avoided. But there are cases where a Cartesian product is highly desirable. This post shows you an example query—from the real world although presented here ...

This is the third installment of my posts on the performance impact of enabling SQL Server 2008 R2 Audit. My previous two posts (part I and part II) show that whether it’s on a two-processor machine or an eight-processor machine, enabling an audit with the queue_delay property set to 0 can destroy the database performance. In particular, those two ...