Missing Index DMV Limitations

Brent Ozar goes into detail on why you should not blindly trust missing index recommendations in SQL Server:

SQL Server’s telling us that it needs an index to do an equality search on LastAccessDate – because our query says LastAccessDate = ‘2016/11/10’.

But in reality, that’s not how you access datetime fields because it won’t give you everyone who accessed the system on 2016/11/10 – it only gives you 2016/11/10 00:00:00. Instead, you need to see everyone on that day, like this:

Read the whole thing.  The crux of this is that the missing index recommendation process only gets to see what you’re running at the time you run it, so it can’t generalize all that well; that’s your job.

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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