SARGable

Shane O’Neill explains what SARGable means and why it’s important:

So now that 1). we have our table and b). we have an index we can use, we can run the developer’s query and be SARGable right?

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DECLARE @Year INT = 2016;
SELECT [Test_Date] FROM [dbo].[DateTest] WHERE YEAR([Test_Date]) = @Year;
GO

Nope! Table scan, ignores our Index and reads all 15M (too lazy for all the zeros) for a measely 127,782 rows! It’s not the slowest, taking around 3.960 seconds but still, we want SARGable!!!

Watch for the surprise twist at the end.

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