SQL Server Blog

SQLBits VI comes to London on the 16th April 2010.

The event is being promoted as the best event yet and best of all…it’s free! So register today!

SQLBits

You may have seen the term SARGable in blogs or forums and wondered what it means. To start with, SARGable is pseudo-acronym which stands for Search ARGument. A query is considered sargable if the WHERE clause can take advantage of an index to speed up the query. A non-sargable query implies that the WHERE clause (or part of it) cannot use any available indexes which could result in a table or index scan and possibly slow down query performance.

You could possibly have a non-sargable query if you use filters like <>, !=, NOT, NOT IN, LIKE ‘%Clive’, NOT LIKE and NOT EXISTS. These filters could cause the optimiser to not use an index, although not always!

Filters such as =, >, <, <=, >=, IN, LIKE ‘Clive%’ could allow the optimiser to use available indexes to speed up query performance.