O'Reilly logo

Microsoft® SQL Server 2012 Unleashed by Alex T. Silverstein, Chris Gallelli, Paul T. Bertucci, Ray Rankins

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Optimizing with Filtered Indexes

SQL Server 2012 provides the ability to define filtered indexes and statistics on a subset of rows rather than on the entire rowset in a table. This is done by specifying simple predicates in the index create statement to restrict the set of rows included in the index. Filtered statistics help solve a common problem in estimating the number of matching rows when the estimates become skewed due to a large number of duplicate values (or NULLs) in an index or due to data correlation between columns. Filtered indexes provide query optimization benefits when you frequently query specific subsets of your data rows.

If a filtered index exists on a table, the optimizer recognizes when a search predicate is compatible ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required