Indexed Columns : Manage lists and libraries with many items

When the number of items in a SharePoint List or SharePoint Document Library increases gradually the performance of the list or library may begin to slow down or adversely affect other areas of the SharePoint site. Such issues can be caused by user actions such as sorting or filtering or retrieving a large number of items at the same time. However, you can save millions of items in lists and libraries as long as you plan and configure the list or library correctly.

List View Threshold:
SharePoint has a List View Threshold of 5,000 items. The purpose of this threshold is to ensure SharePoint servers can run reliably and not get overwhelmed, so performance is not affected.

Creating indexed columns:
To improve the performance of a large list or library, you can index a column. An index on a column enables Windows SharePoint Services 3.0 to quickly analyze the data in that column, even when working with thousands or millions of items. For a view to quickly filter through a large number of items, the filter must be applied to a column that is indexed.

It is important to consider the following when you create and use indexed columns:

• Each additional column index consumes extra resources in the database. Therefore, you should add indexes only to columns that will be used actively in views on the list or library.
• When you define a view in a list or library with lots of items, it is important to use a filter that will return no more than two thousand items.
• Only one indexed column can be used in a view filter. You can filter on many different columns, but it is important that the first column that you use to filter the view has an index and that it sufficiently reduces the total number of items returned.
• Defining a view that uses an OR filter does not have any benefits of an indexed column.
• Defining an item limit in a view does not have the same benefits as filtering by an indexed column.

To Create an Indexed Column:

1. Click on List/Library Settings.
2. Under Columns, click Indexed columns.
3. Select the check box next to each column that you want to index.
4. Click OK.

Important: Please note that a Lookup column that has been set to “Allow multiple values” cannot be indexed and will not appear on the Indexed Columns page.