Editing Full-text search (section)

===Improved querying tools===

*[[Index term|Keyword]]s. Document creators (or trained indexers) are asked to supply a list of words that describe the subject of the text, including synonyms of words that describe this subject. Keywords improve recall, particularly if the keyword list includes a search word that is not in the document text.
* [[Field-restricted search]]. Some search engines enable users to limit full text searches to a particular [[field (computer science)|field]] within a stored [[Record (computer science)|data record]], such as "Title" or "Author."
* {{visible anchor|Boolean queries}}. Searches that use [[Boolean logic|Boolean]] operators (for example, {{mono|"encyclopedia" [[Logical conjunction|AND]] "online" [[Negation|NOT]] "Encarta"}}) can dramatically increase the precision of a full text search. The {{mono|AND}} operator says, in effect, "Do not retrieve any document unless it contains both of these terms." The {{mono|NOT}} operator says, in effect, "Do not retrieve any document that contains this word." If the retrieval list retrieves too few documents, the {{mono|OR}} operator can be used to increase [[recall (information retrieval)|recall]]; consider, for example, {{mono|"encyclopedia" AND "online" [[Logical disjunction|OR]] "Internet" NOT "Encarta"}}. This search will retrieve documents about online encyclopedias that use the term "Internet" instead of "online." This increase in precision is very commonly counter-productive since it usually comes with a dramatic loss of recall.<ref>[http://eprints.cs.vt.edu/archive/00000112/ Experimental Comparison of Schemes for Interpreting Boolean Queries]</ref>
* [[Phrase search]]. A phrase search matches only those documents that contain a specified phrase, such as {{mono|"Wikipedia, the free encyclopedia."}}
* [[Concept search]]. A search that is based on multi-word concepts, for example [[Compound term processing]]. This type of search is becoming popular in many e-discovery solutions.
* [[Concordance search]]. A concordance search produces an alphabetical list of all principal words that occur in a [[Plain text|text]] with their immediate context.
* [[Proximity search (text)|Proximity search]]. A phrase search matches only those documents that contain two or more words that are separated by a specified number of words; a search for {{mono|"Wikipedia" WITHIN2 "free"}} would retrieve only those documents in which the words {{mono|"Wikipedia" and "free"}} occur within two words of each other.
* [[Regular expression]]. A regular expression employs a complex but powerful querying [[syntax]] that can be used to specify retrieval conditions with precision.
* [[Fuzzy search]] will search for document that match the given terms and some variation around them (using for instance [[edit distance]] to threshold the multiple variation)
* [[Wildcard character|Wildcard search]]. A search that substitutes one or more characters in a search query for a wildcard character such as an [[asterisk]]. For example, using the asterisk in a search query {{mono|"s*n"}} will find "sin", "son", "sun", etc. in a text.