column indexing and sql profiler
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26-06-2021 - |
Pregunta
I have enabled sql profiler and identified several queries that are taking a long time to execute.
For example:
Select A from table_A where B = 2
My question is, based on above query, do I create indexes on column A or B? or A and B?
Solución
Index on B
including column A
. The where can use a seek on B
while still returning A
.
Otros consejos
Your index should be on B since that's what is in your condition. You might benefit from just trying out all the ways and looking at the resulting execution plans.
I would create an index on column B because that is what sql server is doing the comparison on. Afterwards I would run the profiler again to see if adding the index negatively impacts other queries.
Create seperate indexes on B and A. Creating index on A is to avoid KEY LOOKUP.