Customizing search results in SharePoint

Learn how to group similar items or remove duplicate items in a search result set in SharePoint so you can display these results in a concise, readable way.

In search results, grouping collapses two or more similar items in a search result set to make their display more readable for a user. Duplicate removal of search results is a part of grouping, where items that are identical or nearly identical are removed from the result set. Depending on the settings set by the SharePoint administrator, the user might be able to expand the search result set later and see the individual results that were collapsed.

The following are examples of ways to group search results:

• Duplicate detection, where nearly identical documents are removed from the result set.
• Site collapsing, where only the most relevant item found in each site is shown in the result set.
• Document set collapsing, where only one hit is displayed for each document library in SharePoint.

You can specify the criteria for collapsing or duplicate trimming programmatically by using the following KeywordQuery properties within the Query object model:

• CollapseSpecification
• TrimDuplicates
• TrimDuplicatesOnProperty
• TrimDuplicatesKeepCount
• TrimDuplicatesIncludeId

Collapse similar search results using the CollapseSpecification property

The CollapseSpecification property takes a Spec parameter that can contain multiple fields separated either by a comma or a space, which evaluated together specify a set of criteria used for collapsing.

Syntax CollapseSpecification = Spec

The following table lists the fields of the Spec parameter.

Table 1. Spec parameter fields

If the fields in Spec are separated by commas, the fields are combined by using the AND operator. If all of the specified fields are matched, the items are collapsed.

In contrast, if the fields in Spec are separated by spaces, the fields (or Subspecs) are combined by using an expansion that includes both the AND operator and OR operator. For example, an expression such as Category:3 Product:2 is internally transformed to the following expression (Category AND Product) OR (Category) with a counter for each; hence a maximum of two of the former and three of the latter. Items are collapsed if some of the specified fields are matched.

Examples of using CollapseSpecification

The following table shows a product catalog from the Contoso company. The next set of examples use this catalog to show how the CollapseSpecification property works.

Example: group by Category

First, group the items based on Category and show the top two (hence "Category:2") for each group. Then, for each Category, show a corresponding number of unique (hence "Product:1") Products.

Syntax CollapseSpecification="Category:2 Product:1"

This should return the following results.

Use the following code to collapse the search results by using the CollapseSpecification property.

using (var context = new ClientContext("http://localhost"))
{
    var query = new KeywordQuery(context)
        {
            QueryText = "Title:Computer",
            CollapseSpecification = "Category:3 Product:1",
        };

    var executor = new SearchExecutor(context);
    var results = executor.ExecuteQuery(query);

    context.ExecuteQuery();

    foreach (var result in results.Value[0].ResultRows)
    {
        Console.WriteLine(result["Title"]);
    }
}

Example: group by Category and Product

First, group the items based on both Category and Product. Then, show each unique combination.

Syntax CollapseSpecification="Category,Product:1"

This should return the following results.

Trim duplicate search results using the TrimDuplicates property

Use TrimDuplicates to specify whether to trim away the duplicate search results from the result set. TrimDuplicates is true by default.

If you use TrimDuplicates with either TrimDuplicatesOnProperty or preferably CollapseSpecification, TrimDuplicates is set to false.

Syntax TrimDuplicates = <$true | $false>

Trim duplicate search results using the TrimDuplicatesOnProperty property

Use TrimDuplicatesOnProperty to specify whether to use a non-default managed property as the basis for duplicate trimming. The default value is the DocumentSignature managed property. The managed property must be of type Integer or String. By using a managed property that represents a grouping of items, you can use this feature for field collapsing.

Syntax TrimDuplicatesOnProperty = <managed property>

Trim duplicate search results using the TrimDuplicatesKeepCount property

Use TrimDuplicatesKeepCount to specify the number of documents to retain when TrimDuplicates is true. 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 those with the highest dynamic rank within each group.

Syntax TrimDuplicatesKeepCount = <number>

Retrieve duplicate search results using the TrimDuplicatesIncludeId property

Use TrimDuplicatesIncludeId to retrieve the duplicates of a document when TrimDuplicates is true and TrimDuplicatesOnProperty or CollapseSpecification is set to false.

The document ID, docid, is used to retrieve the duplicates of a particular document.

Syntax TrimDuplicatesIncludeId = <docid>

See also

• KeywordQuery
• Overview of the search schema in SharePoint