Here's a quick tip for you:During some restore operations on Microsoft SQL Server, the transaction log redo step might be taking an unusually long time.  Depending somewhat on the version and edition of SQL Server you've installed, you may be able to increase performance by tinkering with the readahead performance for the redo operations. ...

An especially clever community member was kind enough to reverse-engineer the video stream for me, and came up with a direct link to the PASS TV video stream for my Query Tuning Mastery: The Art and Science of Manhandling Parallelism talk, delivered at the PASS Summit last Thursday. I'm not sure how long this link will work, but I'd like to share ...

For the second year in a row, I was asked to deliver a 500-level ''Query Tuning Mastery'' talk in room 6E of the Washington State Convention Center, for the PASS Summit. (Here's some information about last year's talk, on workspace memory.) And for the second year in a row, I had to deliver said talk at 10:15 in the morning, in a room used as ...

The PerfMon Counters That Just Won't DieOne of the things that's simultaneously great and horrible about the Internet is that once something gets posted out in the ether, it basically never goes away.  (Some day, politicians will realize this.  We can easily fact check their consistency).  Because of longevity of content posted to ...

As some of you might know, I have been to SQLRally Nordic 2012 in Copenhagen earlier this week. I was able to attend many interesting sessions, I had a great time catching up with old friends and meeting new people, and I was allowed to present a session myself. I understand that the PowerPoint slides and demo code I used in my session will be ...

Given a partitioned table and a simple SELECT query that compares the partitioning column to a single literal value, why does SQL Server read all the partitions when it seems obvious that only one partition needs to be examined? Sample Data The following script creates a table, partitioned on the char(3) column ‘Div’, and populates it with ...

The humble Compute Scalar is one of the least well-understood of the execution plan operators, and usually the last place people look for query performance problems.  It often appears in execution plans with a very low (or even zero) cost, which goes some way to explaining why people ignore it. Some readers will already know that a Compute ...

Can DELETE operations cause pages to split?  Yes.  It sounds counter-intuitive on the face of it; deleting rows frees up space on a page, and page splitting occurs when a page needs additional space.  Nevertheless, there are circumstances when deleting rows causes them to expand before they can be deleted.  The mechanism at ...

I had the honor of traveling the great state of Colorado last week, speaking at the PASS chapters in Boulder, Colorado Springs, and Denver.  At all three events, we had a stellar attendance and, at least in Denver, broke all the records in recent memory both in terms of overall attendance and in first-timers. ...

I showed why T-SQL scalar user-defined functions are bad for performance in two previous posts. In this post, I will show that CLR scalar user-defined functions are bad as well (though not always quite as bad as T-SQL scalar user-defined functions). I will admit that I had not really planned to cover CLR in this series. But shortly after ...