Thursday, July 9, 2015

Difference between Filtered and Indexed View



Difference between Filtered Index and Indexed View

Filtered indexes have the following advantages over indexed views-

Criteria
Filtered Index
Indexed Views
Maintenance Costs
Reduced index maintenance costs because the query processor uses fewer CPU resources to update a filtered index
The query processor uses more CPU resources to update a Indexed View.
Plan Quality
Improved plan quality because during query compilation, the query optimizer considers using a filtered index in more situations
They are not so benificial in the query optimizer as Filtered Index
Online index rebuilds
A Filtered indexes while they are available for queries
Online index rebuilds are not supported for indexed views
Non-unique indexes
Filtered indexes can be non-unique
Indexed views must be unique
Only One Table
A Filtered Index is created on column(s) of a particular table.
Index Views can be created on column(s) from multiple base tables.
Simple WHERE criteria
A Filtered Index can not use complex logic in its WHERE clause, for example the LIKE clause, NOT IN, OR and dynamic / non-deterministic predicates like WHERE col >= DATEADD(DAY, -1, GETDATE()) are not allowed, only simple comparison operators are allowed.
This limitation does not apply to indexed views and you can design your criteria as complex as you want.



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