11.10 SPPS Search Ranking

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SharePoint Portal Server offers an advanced ranking algorithm, based on work undertaken by Microsoft Research. This algorithm ensures that the documents most relevant to a user's query are returned at the top of the list of search results, based upon a probabilistic ranking of searched material.

The ranking of a document is based upon a number of factors, including:

• Document length

• Frequency of the query term in the entire collection of documents

• Number of documents in the entire collection of documents

• Number of documents containing the query term

To force certain documents or files to appear higher up a ranking, Best Bets can be used. This feature enables users with appropriate permissions to tag individual documents as most appropriate for specific queries or categories. Even in the most advanced probabilistic ranking environment, certain documents lack the textual information to be prominent in search results for particular terms.

The Best Bets feature addresses this problem, either by advancing the specially tagged documents to the top of the results list or by displaying them prominently when browsing categories. The SharePoint Portal Server dashboard site also nominates Best Bet documents when the rank of the document is very high.

11.10.1 Automatic Categorization and Schema Support

In addition to simple search, SharePoint Portal Server provides automatic categorization. This feature enables the user to define a category hierarchy and then use a sample set of documents within the hierarchy as a training sample. After training, documents stored on the server and crawled documents are automatically tagged and appear in the category hierarchy.

SharePoint Portal Server provides simplified schema management facilities, which are Office compatible through the use of promotion and demotion. Users define document profiles and associated properties. During promotion, property values in the Office document are copied to the properties of a SharePoint Portal Server document profile. During demotion, property values found in a SharePoint Portal Server document profile are copied to the Office document. Full-text search in SharePoint Portal Server is tightly integrated with that schema. Advanced search uses properties and document profiles.

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