Microsoft SharePoint Server 2010 search and Microsoft FAST Search Server 2010 for SharePoint provides two approaches for processing queries to return search results:
- Content crawling: In this approach, results are returned from the Search service application’s content index based on the user’s query. The content index contains content that is crawled by the Search service application, and includes text content and metadata for each content item.
- Federated search: In this approach, you are enabled to display search results for additional content that is not crawled by your search server. With federation, the query can be performed over the local content index, or it can be forwarded to an external content repository where it is processed by that repository’s search engine. The repository’s search engine then returns the results to the search server. The search server formats and renders the results from the external repository within the same search results page as the results from the search server’s own content index.
To help you decide whether to crawl a repository’s content directly or by using federated search, you should consider the differences between the two approaches. You must determine which is most appropriate based on the content repository, and your requirements for the search results you want to return. There are advantages to both approaches.
Advantages of crawling content with SharePoint Enterprise Search
By querying the Search service application’s content index for search results, you can do the following:
- Sort results by relevance.
- Control how frequently the content index is updated.
- Specify what metadata is crawled.
- Perform a single backup operation for crawled content.
Advantages of federating content with SharePoint Enterprise Search
By using federated search to return search results:
- You require no additional capacity requirements for the content index, as content is not crawled by SharePoint Enterprise Search.
- You can take advantage of a repository’s existing search engine. For example, you can federate to an Internet search engine to search the Web.
- You can optimize the content repository’s search engine for the repository’s specific set of content, which might provide better search performance on the content set.
- You can access repositories that are secured against crawls, but which can be accessed by search queries.