Duplicate Removal (FAST Search Server 2010 for SharePoint)

SharePoint 2010

You can apply duplicate removal (duplicate trimming) to query results based on the value of a given managed property.

Last modified: August 30, 2011

You can also use this feature to collapse hits in the result set by a group identifier (includedid).

Applies to: SharePoint Server 2010

For the Query Web service, you specify criteria for duplicate trimming by using the TrimDuplicates Element in Microsoft.Search.Query Schema.

For the Query object model, you specify criteria for duplicate trimming by using the following properties of KeywordQuery: TrimDuplicates, TrimDuplicatesOnProperty, TrimDuplicatesKeepCount, and TrimDuplicatesIncludeId.

The following table specifies the attributes or properties that can be used in queries to control duplicate trimming.

Table 1. Attributes and properties to control duplicate trimming

Attribute or Property



Specifies the name of a non-default managed property to use as the basis for duplicate removal. The default value is the DocumentSignature managed property.

The managed property must be of type Integer. By using a managed property that represents a grouping of items, you can use this feature for field collapsing.


Specifies the number of items to keep for each set of duplicates. The default value is 1.

It can be used for result collapsing use cases. If TrimDuplicates is based on a managed property that can be used as a group identifier (for example, a site ID), you can control how many results are returned for each group. The items returned are the items with the highest dynamic rank within each group.


Specifies the value associated with a collapse group, typically used when a user clicks the Duplicates (n) link of an item with duplicates.

This value corresponds to the value of the fcoid managed property that is returned in query results.

For more information, see Managed Properties and Data Types (FAST Search Server 2010 for SharePoint).