mirror of https://github.com/apache/lucene.git
398 lines
17 KiB
DTD
398 lines
17 KiB
DTD
<!--
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<h3>Background</h3>
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This DTD describes the XML syntax used to perform advanced searches using the core Lucene search engine. The motivation behind the XML query syntax is:
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<ol>
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<li>To open up Lucene functionality to clients other than Java</li>
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<li>To offer a form of expressing queries that can easily be
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<ul>
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<li>Persisted for logging/auditing purposes</li>
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<li>Changed by editing text query templates (XSLT) without requiring a recompile/redeploy of applications</li>
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<li>Serialized across networks (without requiring Java bytecode for Query logic deployed on clients)</li>
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</ul>
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</li>
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<li>To provide a shorthand way of expressing query logic which echos the logical tree structure of query objects more closely than reading procedural Java query construction code</li>
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<li>To bridge the growing gap between Lucene query/filtering functionality and the set of functionality accessible throught the standard Lucene QueryParser syntax</li>
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<li>To provide a simply extensible syntax that does not require complex parser skills such as knowledge of JavaCC syntax</li>
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</ol>
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<h3>Syntax overview</h3>
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Search syntax consists of two types of elements:
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<ul>
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<li><i>Queries</i></li>
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<li><i>Filters</i></li>
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</ul>
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<h4>Queries</h4>
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The root of any XML search must be a <i>Query</i> type element used to select content.
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Queries typically score matches on documents using a number of different factors in order to provide relevant results first.
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One common example of a query tag is the <a href="#UserQuery">UserQuery</a> element which uses the standard
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Lucene QueryParser to parse Google-style search syntax provided by end users.
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<h4>Filters</h4>
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Unlike Queries, <i>Filters</i> are not used to select or score content - they are simply used to filter <i>Query</i> output (see <a href="#FilteredQuery">FilteredQuery</a> for an example use of query filtering).
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Because Filters simply offer a yes/no decision for each document in the index their output can be efficiently cached in memory as a <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/util/BitSet.html">Bitset</a> for
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subsequent reuse (see <a href="#CachedFilter">CachedFilter</a> tag).
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<h4>Nesting elements</h4>
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Many of the the elements can nest other elements to produce queries/filters of an arbitrary depth and complexity.
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The <a href="#BooleanQuery">BooleanQuery</a> element is one such example which provides a means for combining other queries (including other BooleanQueries) using Boolean
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logic to determine mandatory or optional elements.
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<h3>Advanced topics</h3>
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<h4>Advanced positional testing - span queries</h4>
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The <i>SpanQuery</i> class of queries allow for complex positional tests which not only look for certain combinations of words but in particular
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positions in relation to each other and the documents containing them.
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CoreParser.java is the Java class that encapsulates this parser behaviour.
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@title Core Lucene
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-->
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<!-- @hidden Define core types of XML elements -->
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<!ENTITY % coreSpanQueries "SpanOr|SpanNear|SpanOrTerms|SpanFirst|SpanNot|SpanTerm" >
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<!ENTITY % coreQueries "BooleanQuery|UserQuery|FilteredQuery|TermQuery|TermsQuery|MatchAllDocsQuery|ConstantScoreQuery" >
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<!ENTITY % coreFilters "RangeFilter|CachedFilter" >
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<!-- @hidden Allow for extensions -->
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<!ENTITY % extendedSpanQueries1 " " >
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<!ENTITY % extendedQueries1 " " >
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<!ENTITY % extendedFilters1 " " >
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<!ENTITY % spanQueries "%coreSpanQueries;%extendedSpanQueries1;" >
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<!ENTITY % queries "%coreQueries;|%spanQueries;%extendedQueries1;" >
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<!ENTITY % filters "%coreFilters;%extendedFilters1;" >
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<!--
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BooleanQuerys implement Boolean logic which controls how multiple Clauses should be interpreted.
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Some clauses may represent optional Query criteria while others represent mandatory criteria.
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@example
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<em>Find articles about banks, preferably talking about mergers but nothing to do with "sumitomo"</em>
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%
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<BooleanQuery fieldName="contents">
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<Clause occurs="should">
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<TermQuery>merger</TermQuery>
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</Clause>
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<Clause occurs="mustnot">
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<TermQuery>sumitomo</TermQuery>
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</Clause>
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<Clause occurs="must">
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<TermQuery>bank</TermQuery>
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</Clause>
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</BooleanQuery>
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%
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-->
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<!ELEMENT BooleanQuery (Clause)+>
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<!-- Optional boost for matches on this query. Values > 1 -->
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<!ATTLIST BooleanQuery boost CDATA "1.0">
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<!-- fieldName can optionally be defined here as a default attribute used by all child elements -->
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<!ATTLIST BooleanQuery fieldName CDATA #IMPLIED>
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<!-- The "Coordination factor" rewards documents that contain more of the optional clauses in this list. This flag can be used to turn off this factor. -->
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<!ATTLIST BooleanQuery disableCoord (true | false) "false">
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<!-- The minimum number of optional clauses that should be present in any one document before it is considered to be a match. -->
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<!ATTLIST BooleanQuery minimumNumberShouldMatch CDATA "0">
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<!-- NOTE: "Clause" tag has 2 modes of use - inside <BooleanQuery> in which case only "query" types can be
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child elements - while in a <BooleanFilter> clause only "filter" types can be contained.
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@hidden TODO: Change BooleanFilterBuilder and BooleanQueryBuilder to auto-wrap choice of query or filters. This type of
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code already exists in CachedFilter so could be reused.
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-->
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<!ELEMENT Clause (%queries;|%filters;)>
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<!-- Controls if the clause is optional (should), mandatory (must) or unacceptable (mustNot) -->
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<!ATTLIST Clause occurs (should | must | mustnot) "should">
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<!-- Caches any nested query or filter in an LRU (Least recently used) Cache. Cached queries, like filters, are turned into
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Bitsets at a cost of 1 bit per document in the index. The memory cost of a cached query/filter is therefore numberOfDocsinIndex/8 bytes.
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Queries that are cached as filters obviously retain none of the scoring information associated with results - they retain just
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a Boolean yes/no record of which documents matched.
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@example
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<em>Search for documents about banks from the last 10 years - caching the commonly-used "last 10 year" filter as a BitSet in
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RAM to eliminate the cost of building this filter from disk for every query</em>
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%
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<FilteredQuery>
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<Query>
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<UserQuery>bank</UserQuery>
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</Query>
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<Filter>
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<CachedFilter>
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<RangeFilter fieldName="date" lowerTerm="19970101" upperTerm="20070101"/>
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</CachedFilter>
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</Filter>
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</FilteredQuery>
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%
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-->
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<!ELEMENT CachedFilter (%queries;|%filters;)>
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<!--
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Passes content directly through to the standard LuceneQuery parser see "Lucene Query Syntax"
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@example
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<em>Search for documents about John Smith or John Doe using standard LuceneQuerySyntax</em>
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%
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<UserQuery>"John Smith" OR "John Doe"</UserQuery>
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%
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-->
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<!ELEMENT UserQuery (#PCDATA)>
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<!-- Optional boost for matches on this query. Values > 1 -->
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<!ATTLIST UserQuery boost CDATA "1.0">
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<!-- A query which is used to match all documents. This has a couple of uses:
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<ol>
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<li> as a Clause in a BooleanQuery who's only other clause
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is a "mustNot" match (Lucene requires at least one positive clause) and..</li>
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<li> in a FilteredQuery where a Filter tag is effectively being
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used to select content rather than it's usual role of filtering the results of a query.</li>
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</ol>
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@example
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<em>Effectively use a Filter as a query </em>
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%
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<FilteredQuery>
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<Query>
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<MatchAllDocsQuery/>
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</Query>
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<Filter>
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<RangeFilter fieldName="date" lowerTerm="19870409" upperTerm="19870412"/>
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</Filter>
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</FilteredQuery>
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%
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-->
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<!ELEMENT MatchAllDocsQuery EMPTY>
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<!-- a single term query - no analysis is done of the child text
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@example
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<em>Match on a primary key</em>
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%
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<TermQuery fieldName="primaryKey">13424</TermQuery>
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%
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-->
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<!ELEMENT TermQuery (#PCDATA)>
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<!-- Optional boost for matches on this query. Values > 1 -->
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<!ATTLIST TermQuery boost CDATA "1.0">
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<!-- fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute -->
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<!ATTLIST TermQuery fieldName CDATA #IMPLIED>
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<!--
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The equivalent of a BooleanQuery with multiple optional TermQuery clauses.
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Child text is analyzed using a field-specific choice of Analyzer to produce a set of terms that are ORed together in Boolean logic.
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Unlike UserQuery element, this does not parse any special characters to control fuzzy/phrase/boolean logic and as such is incapable
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of producing a Query parse error given any user input
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@example
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<em>Match on text from a database description (which may contain characters that
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are illegal characters in the standard Lucene Query syntax used in the UserQuery tag</em>
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%
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<TermsQuery fieldName="description">Smith & Sons (Ltd) : incorporated 1982</TermsQuery>
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%
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-->
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<!ELEMENT TermsQuery (#PCDATA)>
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<!-- Optional boost for matches on this query. Values > 1 -->
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<!ATTLIST TermsQuery boost CDATA "1.0">
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<!-- fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute -->
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<!ATTLIST TermsQuery fieldName CDATA #IMPLIED>
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<!-- The "Coordination factor" rewards documents that contain more of the terms in this list. This flag can be used to turn off this factor. -->
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<!ATTLIST TermsQuery disableCoord (true | false) "false">
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<!-- The minimum number of terms that should be present in any one document before it is considered to be a match. -->
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<!ATTLIST TermsQuery minimumNumberShouldMatch CDATA "0">
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<!--
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Runs a Query and filters results to only those query matches that also match the Filter element.
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@example
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<em>Find all documents about Lucene that have a status of "published"</em>
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%
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<FilteredQuery>
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<Query>
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<UserQuery>Lucene</UserQuery>
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</Query>
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<Filter>
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<TermsFilter fieldName="status">published</TermsFilter>
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</Filter>
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</FilteredQuery>
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%
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-->
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<!ELEMENT FilteredQuery (Query,Filter)>
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<!-- Optional boost for matches on this query. Values > 1 -->
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<!ATTLIST FilteredQuery boost CDATA "1.0">
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<!-- Used to identify a nested Query element inside another container element. NOT a top-level query tag -->
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<!ELEMENT Query (%queries;)>
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<!-- The choice of Filter that MUST also be matched -->
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<!ELEMENT Filter (%filters;)>
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<!--
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Filter used to limit query results to documents matching a range of field values
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@example
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<em>Search for documents about banks from the last 10 years</em>
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%
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<FilteredQuery>
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<Query>
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<UserQuery>bank</UserQuery>
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</Query>
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<Filter>
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<RangeFilter fieldName="date" lowerTerm="19970101" upperTerm="20070101"/>
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</Filter>
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</FilteredQuery>
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%
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-->
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<!ELEMENT RangeFilter EMPTY>
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<!-- fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute -->
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<!ATTLIST RangeFilter fieldName CDATA #IMPLIED>
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<!-- The lower-most term value for this field (must be <= upperTerm) -->
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<!ATTLIST RangeFilter lowerTerm CDATA #REQUIRED>
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<!-- The upper-most term value for this field (must be >= lowerTerm) -->
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<!ATTLIST RangeFilter upperTerm CDATA #REQUIRED>
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<!-- Controls if the lowerTerm in the range is part of the allowed set of values -->
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<!ATTLIST RangeFilter includeLower (true | false) "true">
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<!-- Controls if the upperTerm in the range is part of the allowed set of values -->
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<!ATTLIST RangeFilter includeUpper (true | false) "true">
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<!-- A single term used in a SpanQuery. These clauses are the building blocks for more complex "span" queries which test word proximity
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@example <em>Find documents using terms close to each other about mining and accidents</em>
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%
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<SpanNear slop="8" inOrder="false" fieldName="text">
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<SpanOr>
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<SpanTerm>killed</SpanTerm>
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<SpanTerm>died</SpanTerm>
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<SpanTerm>dead</SpanTerm>
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</SpanOr>
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<SpanOr>
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<SpanTerm>miner</SpanTerm>
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<SpanTerm>mining</SpanTerm>
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<SpanTerm>miners</SpanTerm>
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</SpanOr>
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</SpanNear>
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%
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-->
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<!ELEMENT SpanTerm (#PCDATA)>
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<!-- fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute -->
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<!ATTLIST SpanTerm fieldName CDATA #REQUIRED>
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<!-- A field-specific analyzer is used here to parse the child text provided in this tag. The SpanTerms produced are ORed in terms of Boolean logic
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@example <em>Use SpanOrTerms as a more convenient/succinct way of expressing multiple choices of SpanTerms. This example looks for reports
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using words describing a fatality near to references to miners</em>
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%
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<SpanNear slop="8" inOrder="false" fieldName="text">
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<SpanOrTerms>killed died death dead deaths</SpanOrTerms>
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<SpanOrTerms>miner mining miners</SpanOrTerms>
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</SpanNear>
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%
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-->
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<!ELEMENT SpanOrTerms (#PCDATA)>
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<!-- fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute -->
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<!ATTLIST SpanOrTerms fieldName CDATA #REQUIRED>
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<!-- Takes any number of child queries from the Span family
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@example <em>Find documents using terms close to each other about mining and accidents</em>
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%
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<SpanNear slop="8" inOrder="false" fieldName="text">
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<SpanOr>
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<SpanTerm>killed</SpanTerm>
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<SpanTerm>died</SpanTerm>
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<SpanTerm>dead</SpanTerm>
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</SpanOr>
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<SpanOr>
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<SpanTerm>miner</SpanTerm>
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<SpanTerm>mining</SpanTerm>
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<SpanTerm>miners</SpanTerm>
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</SpanOr>
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</SpanNear>
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%
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-->
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<!ELEMENT SpanOr (%spanQueries;)* >
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<!-- Takes any number of child queries from the Span family and tests for proximity
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@hidden TODO SpanNear missing "boost attr (could add to SpanBuilderBase)
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-->
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<!ELEMENT SpanNear (%spanQueries;)* >
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<!-- defines the maximum distance between Span elements where distance is expressed as word number, not byte offset
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@example <em>Find documents using terms within 8 words of each other talking about mining and accidents</em>
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%
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<SpanNear slop="8" inOrder="false" fieldName="text">
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<SpanOr>
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<SpanTerm>killed</SpanTerm>
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<SpanTerm>died</SpanTerm>
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<SpanTerm>dead</SpanTerm>
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</SpanOr>
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<SpanOr>
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<SpanTerm>miner</SpanTerm>
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<SpanTerm>mining</SpanTerm>
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<SpanTerm>miners</SpanTerm>
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</SpanOr>
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</SpanNear>
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%
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-->
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<!ATTLIST SpanNear slop CDATA #REQUIRED>
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<!-- Controls if matching terms have to appear in the order listed or can be reversed -->
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<!ATTLIST SpanNear inOrder (true | false) "true">
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<!-- Looks for a SpanQuery match occuring near the beginning of a document
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@example
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<em>Find letters where the first 50 words talk about a resignation:</em>
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%
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<SpanFirst end="50">
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<SpanOrTerms fieldName="text">resigning resign leave</SpanOrTerms>
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</SpanFirst>
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%
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-->
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<!ELEMENT SpanFirst (%spanQueries;) >
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<!-- Controls the end of the region considered in a document's field (expressed in word number, not byte offset) -->
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<!ATTLIST SpanFirst end CDATA #REQUIRED>
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<!-- Optional boost for matches on this query. Values > 1 -->
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<!ATTLIST SpanFirst boost CDATA "1.0">
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<!-- Finds documents matching a SpanQuery but not if matching another SpanQuery
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@example <em>Find documents talking about social services but not containing the word "public"</em>
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%
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<SpanNot fieldName="text">
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<Include>
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<SpanNear slop="2" inOrder="true">
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<SpanTerm>social</SpanTerm>
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<SpanTerm>services</SpanTerm>
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</SpanNear>
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</Include>
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<Exclude>
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<SpanTerm>public</SpanTerm>
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</Exclude>
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</SpanNot>
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%
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-->
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<!ELEMENT SpanNot (Include,Exclude) >
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<!-- The SpanQuery to find -->
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<!ELEMENT Include (%spanQueries;) >
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<!-- The SpanQuery to be avoided -->
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<!ELEMENT Exclude (%spanQueries;) >
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<!-- a utility tag to wrap any filter as a query
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@example <em> Find all documents from the last 10 years </em>
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%
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<ConstantScoreQuery>
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<RangeFilter fieldName="date" lowerTerm="19970101" upperTerm="20070101"/>
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</ConstantScoreQuery>
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%
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-->
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<!ELEMENT ConstantScoreQuery (%filters;)* >
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<!-- Optional boost for matches on this query. Values > 1 -->
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<!ATTLIST ConstantScoreQuery boost CDATA "1.0">
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