The Importance Of Index Column Order

Erik Darling shows us how arranging columns in an index can make a huge difference in query performance:

while back I promised I’d write about what allows SQL Server to perform two seeks rather than a seek with a residual predicate.

More recently, a post touched a bit on predicate selectivity in index design, and how missing index requests don’t factor that in when requesting indexes.

This post should tie the two together a bit. Maybe. Hopefully. We’ll see where it goes, eh?

Also apropos: missing index hints return results in alphabetical order, not in selectivity order or what would be best for queries. In other words, just because the green text in SSMS says it’s the index you want doesn’t mean it’s the index you need.

Related Posts

Finding Missing Index Hints in Query Store

Grant Fritchey shows us another place where we can find missing index hints: A couple of notes on the query. I cast the query_plan as xml so that I can use the XQuery to pull out the information. It is possible that the plan might be so large that you get an error because of […]

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Benefits of Inline Indexes

Phil Factor covers a topic fairly close to my heart: Usually, the added features of the CREATE TABLE syntax in new releases of SQL Server are esoteric, and unless you are dealing with memory-optimized tables or other esoteric stuff, they aren’t of great interest. However, the Inline INDEX for both a table and column index […]

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