Month: February 2018

Execution plans 101: (back to) The basics

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?

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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