![]() Although indexes may have duplicate keys, there are important things to be aware about. (Not sure what keys are? Watch How to Think Like the Engine.)ĭuplicate keys are a red flag, but don’t jump into action too soon. Indexes diagnosed with duplicate keys have exactly that: completely duplicate keys. Duplicate indexes take up double the room in SQL Server– and even if indexes are COMPLETELY identical, SQL Server may choose to use both of them.ĭuplicate indexes essentially cost you extra IO, CPU, and Memory, just the things you were trying to SAVE by adding nonclustered indexes! And that’s a little bit crazy. You want to have the right nonclustered indexes in place to help support queries reading table and make them faster– that has a lot of benefits, like reducing IO, CPU, and memory usage.īut on the flip side, you can easily have too much of a good thing. NonClustered indexes are very powerful in SQL Server. What’s so wrong with multiple index personalities? Explanations of disabled indexes are explained here. : If the index contains included columns, this will be present (after the section) and will be followed by a list of the includes.: The list of key columns in the index.Because of this the index_definition is prefixed with codes. ![]() There are other important things you need to know about the indexes. This sorting means that potential duplicates will be next to each other. To understand which index has potential or actual duplicates, look at the index_definition column. Results in this section are sorted by alphabetical order of the list of keys and includes. ![]() Ever feel like there’s more people in the room than need to be there? Our checks say that your indexes feel that way, too. Your indexes have been diagnosed with multiple personality disorder.
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