Terminology for search relevance (FAST Search Server 2010 for SharePoint)

Article
07/22/2014

Applies to: FAST Search Server 2010

Relevance describes how well a given search satisfies a user’s information needs. The following terms are important to search relevance:

Term	Definition
Crawled properties	Crawled properties are metadata extracted from content sources when you run a crawler or connector. Metadata can be structured content such as the title or the author from a Word document, or unstructured content based on the content of an item such as a detected language or extracted keywords. Typically, crawled properties include column data for SharePoint list items, document properties for Microsoft Office or other binary file types, and HTML metadata in web pages.
Managed properties	Administrators map crawled properties to managed properties in order to make metadata searchable and provide useful search experiences. For example, an administrator might create a managed property named Client that maps to various crawled properties called Customer, Client, and Cust from different content repositories. Managed properties can then be used across the search solution, such as in defining search scopes and in applying search filters.
Full-text index	Managed properties are mapped to a full-text index. This enables you to search across several properties at the same time. When a search is performed, it searches in a full-text index.
Index schema	The index schema controls which content parts are indexed, searchable, and available for viewing. It also manages the mapping of managed properties into full-text indexes.
Search item	A searchable item in the index. This can be a document, a list, a list item, a database record, or any other kind of content that is indexed and available for search.
Recall	The number of search items found in the index related to a search. High recall means that many search items are returned.
Rank points	Points that are given to search items based on the importance of each item. The more rank points a search item receives, the higher up it appears in the search results list.
Dynamic rank points	Rank points that are added to search items at search time. The number of points that are given is based on a combination of the search words used and several boost values in the rank profile.
Quality rank points	Also known as Static rank points, are points added to a search items before it is indexed. The number of points given are based on boost values that are stored in predefined quality rank components.
Keyword rank	Rank points that are added to a search item when a search word matches a specified keyword. Each keyword can include a list of associated synonyms, and recall is improved by also searching for these associated synonyms.
Rank score	The sum of all rank points given to a search item during query processing. A search item with a high rank score will appear in the upper end of the search results list.