Month: February 2018

Execution plans 101: (back to) The basics

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I recently received an email from a reader of this blog. Specifically of the plansplaining posts. He wrote that he enjoyed reading it, but he still had some questions. Those questions made me realize that I made a mistake when I started this series. I dove in at the deep end. I assumed a lot of prior knowledge and experience with reading execution plans, but not every reader has that knowledge and that experience. So I decided that for this one post, I will move from the deep end of the pool to the shallow water. In this post I…

T-SQL Tuesday #99: Dealer’s Choice

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Back in 2009, Adam Machanic (b|t) started an initiative that is still going strong: T-SQL Tuesday. This is a monthly blog party. Every second Tuesday of each month, lots of people blog about the same topic, selected by the host for that month. And now, in the 99th installment, I decided to finally join in! For February 2018, our host Aaron Bertrand (b|t) has elected to give bloggers a choice: either share some of the non-tech things that we are passionate about; or go all Aaron-style and tell the world what we consider the worst T-SQL habits that we really…

Plansplaining, part 2. Why scan and spool instead of seek?

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This is the second post in the plansplaining series. Each of these blog posts focuses on a sample execution plan and details exactly how that plan works. In the first post, I covered each individual step of each operator in great detail, to make sure that everyone understands exactly how operators work in the pull-based execution plans. In this post (and all future installments), I will leave out the details that I now assume to be known to my readers. If you did not read part 1 already, I suggest you start there. Sample query The query in this post…

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