Indexing

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Filtered Indexes: Just Add Includes

I found a quirky thing recently While playing with filtered indexes, I noticed something odd. By ‘playing with’ I mean ‘calling them horrible names’ and ‘admiring the way other platforms implemented them‘. I sort of wrote about a similar topic in discussing indexing for windowing functions. It turns out that a recent annoyance could also…
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Does Creating an Indexed View Require Exclusive Locks on an Underlying Table?

An interesting question came up in our SQL Server Performance Tuning course in Chicago: when creating an indexed view, does it require an exclusive lock on the underlying table or tables? Let’s test it out with a simple indexed view run against a non-production environment. (AKA, a VM on my laptop running SQL Server 2014.)…
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Filtered Indexes and IS NOT NULL

Filtered indexes can be tricky. Just getting your queries to use the filtered index can be a real pain. Parameterization may mean it’s “unsafe” to use the filtered index. The optimizer might want the filtered column in your key or include column list when it doesn’t seem like it should have to be there. The…
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Indexing for GROUP BY

It’s not glamorous And on your list of things that aren’t going fast enough, it’s probably pretty low. But you can get some pretty dramatic gains from indexes that cover columns you’re performing aggregations on. We’ll take a quick walk down demo lane in a moment, using the Stack Overflow database. Query outta nowhere! Transact-SQL…
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Indexing for Windowing Functions

Hooray Windowing Functions They do stuff that used to be hard to do, or took weird self-joins or correlated sub-queries with triangular joins to accomplish. That’s when there’s a standalone inequality predicate, usually for getting a running total. With Windowing Functions, a lot of the code complexity and inefficiency is taken out of the picture,…
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