Search
Searching and retrieving information within and across repositories requires an integration of several functions:
- Search engine: program that accepts the request from a user, searches an index, and returns the results page to the user
- Search index file: a file created by a search indexing program which stores indexed data from a site or database for fast search results. An index file requires ongoing updating so that changes within the data source are reflected in search results.
- Search form: an interface to the search tool enabling users to enter search terms and specify their preferences for the search
- Search results list: a list of items that match the search or query term(s). These are usually sorted in a relevance ranking, and the user may be able to control the content and format of the results list
Most information retrieval services make use of one or more of the basic search types: simple, boolean, and proximity.
Boolean search: Boolean search is a form of logical comparison in which operators (eg. AND, OR and NOT) define whether multiple search terms are matched within a section of text.
Proximity search: is an extension of Boolean search which also checks the relative position of terms.
Metasearch: search which returns results from a combination of sources. There may be one index for all sites, or separate indexes which are searched at the same time and the results collated. Searchers are usually informed about which source or service provided each result.
Query languages: machine languages which provide commands, logical operators, and filters which enable a search to retrieve information from data sources and repositories