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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 Read More...
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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 Read More...
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The optimizer is the part of SQL Server that takes your query and reorders and rearranges your query to find the optimal execution plan. In theory. In practice, that doesn’t always work out well. Often, the optimizer manages to come up with brilliant Read More...
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Almost a week has passed after SQLBits X in London , so I guess it’s about time for me to share the slides and demo code of my session on columnstore indexes. After all, I promised people I would do that – especially when I found out that I had enough Read More...
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In part 5 of my series on the bin packing problem, I presented a method that sits somewhere in between the true row-by-row iterative characteristics of the first three parts and the truly set-based approach of the fourth part. I did use iteration, but Read More...
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One of the most common techniques authors use to keep their readers interested is to leave them with a cliff-hanger. It’s what I did when I finished part 4 of my series on the bin packing problem – never intending to leave you all hanging over a cliff Read More...
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Almost a year ago now, I started a series of blog post on the bin packing problem . But after the first three posts, various reasons caused the research I still had to do for the fourth part to be massively delayed. It’s only now that I have finally found Read More...
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I guess that many people using UPDATE … FROM on a daily basis do so without being aware that they are violating all SQL standards. All versions of the ANSI SQL standard that I checked agree that an UPDATE statement has three clauses – the UPDATE clause, Read More...
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In the first post of this series, I explained the bin-packing problem and established a baseline solution. The second post investigated ways to increase the packing efficiency. In none of these posts did I pay particular attention to performance – and Read More...
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In my previous post , I explained the bin packing problem, explained an example scenario, and established a baseline for both speed and efficiency of bin packing algorithms by writing a rather crude cursor-based procedure. In this part, I will look at Read More...
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Some problems can only be solved by brute-forcing every possible combination. The problem with such an approach, is that execution time grows exponentially as the amount of input data grows – so that even on the best possible hardware, you will get inacceptable Read More...
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After making my post on cursor optimization I received some comments that triggered me to do some further investigation. Adam Machanic wrote in my blog’s comments that using SQLCLR to loop over a SqlDataReader would be much faster than any T-SQL based Read More...
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The best way to optimize performance of a cursor is, of course, to rip it out and replace it with set-based logic. But there is still a small category of problems where a cursor will outperform a set-based solution. The introduction of ranking functions Read More...
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Did you know that SQL Server allows stored procedures to have up to 2100 parameters? And more important: do you care? Well, some people do care, and Joe Celko seems to be one of them. If you are a regular reader of SQL Server newsgroups, you probably Read More...
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In a previous posting , I explained a minor problem in the “Bounding Box” and “Dynamic Bounding Box” algorithms I describe in chapter 9 of Adam Machanic ’s book Expert SQL Server 2005 Development . In short, the problem is that I calculated the boundaries Read More...
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