Row Goals Gone Rogue

  This post discusses “row goals“, but with a twist. The point is to illustrate how row goals can cause unnecessarily slow queries. First, run this script: USE tempdb GO IF OBJECT_ID (‘even’) IS NOT NULL DROP TABLE even; IF OBJECT_ID (‘odd’) IS NOT NULL DROP TABLE odd; GO CREATE TABLE even (c1 int, c2…

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Don’t depend on expression short circuiting in T-SQL (not even with CASE)

There are a fair number of blog posts and forum discussions regarding expression short circuiting in T-SQL. Some of the most authoritative posts, like this one, come to the following conclusions: (a) You cannot depend on expression evaluation order for things like “WHERE <expr1> OR <expr2>“, since the optimizer might choose a plan that evaluates…

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