LuceneContribQuery.dtd: Elements - Entities - Source | Intro - Index
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Contrib Lucene

This DTD builds on the core Lucene XML syntax and adds support for features found in the "contrib" section of the Lucene project.

CorePlusExtensionsParser.java is the Java class that encapsulates this parser behaviour.

The features added are:

• LikeThisQuery
Support for querying using large amounts of example text indicative of the users' general area of interest
• FuzzyLikeThisQuery
A style of fuzzy query which automatically looks for fuzzy variations on only the "interesting" terms
• BooleanFilter
Is to Filters what core Lucene's BooleanQuery is to Queries - allows mixing of clauses using Boolean logic
• TermsFilter
Constructs a filter from an arbitrary set of terms (unlike RangeFilter which requires a contiguous range of terms)
• DuplicateFilter
Removes duplicated documents from results where "duplicate" means documents share a value for a particular field (e.g. a primary key)
• BoostingQuery
Influence score of a query's matches in a subtle way which can't be achieved using BooleanQuery

BooleanQuerys implement Boolean logic which controls how multiple Clauses should be interpreted. Some clauses may represent optional Query criteria while others represent mandatory criteria.

Example: Find articles about banks, preferably talking about mergers but nothing to do with "sumitomo"

	          
            <BooleanQuery fieldName="contents">
	             <Clause occurs="should">
		              <TermQuery>merger</TermQuery>
	             </Clause>
	             <Clause occurs="mustnot">
		              <TermQuery>sumitomo</TermQuery>
	             </Clause>
	             <Clause occurs="must">
		              <TermQuery>bank</TermQuery>
	             </Clause>
            </BooleanQuery>

	         

<BooleanQuery>'s children Name Cardinality Clause At least one

<BooleanQuery>'s attributes Name Values Default boost 1.0 disableCoord true, false false fieldName minimumNumberShouldMatch 0

(Clause)+

Optional boost for matches on this query. Values > 1

Default value: 1.0

fieldName can optionally be defined here as a default attribute used by all child elements

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.

Possible values: true, false - Default value: false

The minimum number of optional clauses that should be present in any one document before it is considered to be a match.

Default value: 0

NOTE: "Clause" tag has 2 modes of use - inside <BooleanQuery> in which case only "query" types can be child elements - while in a <BooleanFilter> clause only "filter" types can be contained.

<Clause>'s children Name Cardinality BooleanFilter One or none BooleanQuery One or none BoostingQuery One or none BoostingTermQuery One or none CachedFilter One or none ConstantScoreQuery One or none DuplicateFilter One or none FilteredQuery One or none FuzzyLikeThisQuery One or none LikeThisQuery One or none MatchAllDocsQuery One or none NumericRangeFilter One or none NumericRangeQuery One or none RangeFilter One or none SpanFirst One or none SpanNear One or none SpanNot One or none SpanOr One or none SpanOrTerms One or none SpanTerm One or none TermQuery One or none TermsFilter One or none TermsQuery One or none UserQuery One or none

<Clause>'s attributes Name Values Default occurs should, must, mustnot should

(BooleanQuery | UserQuery | FilteredQuery | TermQuery | TermsQuery | MatchAllDocsQuery | ConstantScoreQuery | BoostingTermQuery | NumericRangeQuery | SpanOr | SpanNear | SpanOrTerms | SpanFirst | SpanNot | SpanTerm | BoostingTermQuery | LikeThisQuery | BoostingQuery | FuzzyLikeThisQuery | RangeFilter | NumericRangeFilter | CachedFilter | TermsFilter | BooleanFilter | DuplicateFilter)

Controls if the clause is optional (should), mandatory (must) or unacceptable (mustNot)

Possible values: should, must, mustnot - Default value: should

Caches any nested query or filter in an LRU (Least recently used) Cache. Cached queries, like filters, are turned into 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. Queries that are cached as filters obviously retain none of the scoring information associated with results - they retain just a Boolean yes/no record of which documents matched.

Example: Search for documents about banks from the last 10 years - caching the commonly-used "last 10 year" filter as a BitSet in RAM to eliminate the cost of building this filter from disk for every query

	          
            <FilteredQuery>
               <Query>
                  <UserQuery>bank</UserQuery>
               </Query>	
               <Filter>
                  <CachedFilter>
                     <RangeFilter fieldName="date" lowerTerm="19970101" upperTerm="20070101"/>
                  </CachedFilter>
               </Filter>	
            </FilteredQuery>
	         

<CachedFilter>'s children Name Cardinality BooleanFilter One or none BooleanQuery One or none BoostingQuery One or none BoostingTermQuery One or none CachedFilter One or none ConstantScoreQuery One or none DuplicateFilter One or none FilteredQuery One or none FuzzyLikeThisQuery One or none LikeThisQuery One or none MatchAllDocsQuery One or none NumericRangeFilter One or none NumericRangeQuery One or none RangeFilter One or none SpanFirst One or none SpanNear One or none SpanNot One or none SpanOr One or none SpanOrTerms One or none SpanTerm One or none TermQuery One or none TermsFilter One or none TermsQuery One or none UserQuery One or none

(BooleanQuery | UserQuery | FilteredQuery | TermQuery | TermsQuery | MatchAllDocsQuery | ConstantScoreQuery | BoostingTermQuery | NumericRangeQuery | SpanOr | SpanNear | SpanOrTerms | SpanFirst | SpanNot | SpanTerm | BoostingTermQuery | LikeThisQuery | BoostingQuery | FuzzyLikeThisQuery | RangeFilter | NumericRangeFilter | CachedFilter | TermsFilter | BooleanFilter | DuplicateFilter)

Passes content directly through to the standard LuceneQuery parser see "Lucene Query Syntax"

Example: Search for documents about John Smith or John Doe using standard LuceneQuerySyntax

	          
               <UserQuery>"John Smith" OR "John Doe"</UserQuery>
	         

<UserQuery>'s attributes Name Values Default boost 1.0 fieldName

Optional boost for matches on this query. Values > 1

Default value: 1.0

fieldName can optionally be defined here to change the default field used in the QueryParser

A query which is used to match all documents. This has a couple of uses:

1. as a Clause in a BooleanQuery who's only other clause is a "mustNot" match (Lucene requires at least one positive clause) and..
2. in a FilteredQuery where a Filter tag is effectively being used to select content rather than it's usual role of filtering the results of a query.

Example: Effectively use a Filter as a query

	          
               <FilteredQuery>
                 <Query>
                    <MatchAllDocsQuery/>
                 </Query>
                 <Filter>
                     <RangeFilter fieldName="date" lowerTerm="19870409" upperTerm="19870412"/>
                 </Filter>	
               </FilteredQuery>	         
	       

This element is always empty.

a single term query - no analysis is done of the child text

Example: Match on a primary key

	          
               <TermQuery fieldName="primaryKey">13424</TermQuery>
	       

<TermQuery>'s attributes Name Values Default boost 1.0 fieldName

Optional boost for matches on this query. Values > 1

Default value: 1.0

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

A boosted term query - no analysis is done of the child text. Also a span member.

(Text below is copied from the javadocs of BoostingTermQuery)

The BoostingTermQuery is very similar to the {

Optional boost for matches on this query. Values > 1

Default value: 1.0

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

The equivalent of a BooleanQuery with multiple optional TermQuery clauses. Child text is analyzed using a field-specific choice of Analyzer to produce a set of terms that are ORed together in Boolean logic. Unlike UserQuery element, this does not parse any special characters to control fuzzy/phrase/boolean logic and as such is incapable of producing a Query parse error given any user input

Example: Match on text from a database description (which may contain characters that are illegal characters in the standard Lucene Query syntax used in the UserQuery tag

	          
               <TermsQuery fieldName="description">Smith & Sons (Ltd) : incorporated 1982</TermsQuery>
	       

<TermsQuery>'s attributes Name Values Default boost 1.0 disableCoord true, false false fieldName minimumNumberShouldMatch 0

Optional boost for matches on this query. Values > 1

Default value: 1.0

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

The "Coordination factor" rewards documents that contain more of the terms in this list. This flag can be used to turn off this factor.

Possible values: true, false - Default value: false

The minimum number of terms that should be present in any one document before it is considered to be a match.

Default value: 0

Runs a Query and filters results to only those query matches that also match the Filter element.

Example: Find all documents about Lucene that have a status of "published"

	          
               <FilteredQuery>
                 <Query>
                    <UserQuery>Lucene</UserQuery>
                 </Query>
                 <Filter>
                     <TermsFilter fieldName="status">published</TermsFilter>
                 </Filter>	
               </FilteredQuery>	         
	       

<FilteredQuery>'s children Name Cardinality Filter Only one Query Only one

<FilteredQuery>'s attributes Name Values Default boost 1.0

(Query, Filter)

Optional boost for matches on this query. Values > 1

Default value: 1.0

Used to identify a nested Query element inside another container element. NOT a top-level query tag

<Query>'s children Name Cardinality BooleanQuery One or none BoostingQuery One or none BoostingTermQuery One or none ConstantScoreQuery One or none FilteredQuery One or none FuzzyLikeThisQuery One or none LikeThisQuery One or none MatchAllDocsQuery One or none NumericRangeQuery One or none SpanFirst One or none SpanNear One or none SpanNot One or none SpanOr One or none SpanOrTerms One or none SpanTerm One or none TermQuery One or none TermsQuery One or none UserQuery One or none

(BooleanQuery | UserQuery | FilteredQuery | TermQuery | TermsQuery | MatchAllDocsQuery | ConstantScoreQuery | BoostingTermQuery | NumericRangeQuery | SpanOr | SpanNear | SpanOrTerms | SpanFirst | SpanNot | SpanTerm | BoostingTermQuery | LikeThisQuery | BoostingQuery | FuzzyLikeThisQuery)

The choice of Filter that MUST also be matched

<Filter>'s children Name Cardinality BooleanFilter One or none CachedFilter One or none DuplicateFilter One or none NumericRangeFilter One or none RangeFilter One or none TermsFilter One or none

(RangeFilter | NumericRangeFilter | CachedFilter | TermsFilter | BooleanFilter | DuplicateFilter)

Filter used to limit query results to documents matching a range of field values

Example: Search for documents about banks from the last 10 years

	          
            <FilteredQuery>
               <Query>
                  <UserQuery>bank</UserQuery>
               </Query>	
               <Filter>
                     <RangeFilter fieldName="date" lowerTerm="19970101" upperTerm="20070101"/>
               </Filter>	
            </FilteredQuery>
	         

<RangeFilter>'s attributes
Name	Values	Default
fieldName
includeLower	true, false	true
includeUpper	true, false	true
lowerTerm
upperTerm

This element is always empty.

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

The lower-most term value for this field (must be <= upperTerm)

Required

The upper-most term value for this field (must be >= lowerTerm)

Required

Controls if the lowerTerm in the range is part of the allowed set of values

Possible values: true, false - Default value: true

Controls if the upperTerm in the range is part of the allowed set of values

Possible values: true, false - Default value: true

A Query that matches numeric values within a specified range.

Example: Search for documents about people who are aged 20-25

	          
            <NumericRangeQuery fieldName="age" lowerTerm="20" upperTerm="25" />
	         

<NumericRangeQuery>'s attributes
Name	Values	Default
fieldName
includeLower	true, false	true
includeUpper	true, false	true
lowerTerm
precisionStep		4
type	int, long, float, double	int
upperTerm

This element is always empty.

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

The lower-most term value for this field (must be <= upperTerm and a valid native java numeric type)

Required

The upper-most term value for this field (must be >= lowerTerm and a valid native java numeric type)

Required

The numeric type of this field

Possible values: int, long, float, double - Default value: int

Controls if the lowerTerm in the range is part of the allowed set of values

Possible values: true, false - Default value: true

Controls if the upperTerm in the range is part of the allowed set of values

Possible values: true, false - Default value: true

Lower step values mean more precisions and so more terms in index (and index gets larger). This value must be an integer

Default value: 4

A Filter that only accepts numeric values within a specified range

Example: Search for documents about people who are aged 20-25

	          
            <FilteredQuery>
               <Query>
                  <UserQuery>person</UserQuery>
               </Query>	
               <Filter>
                     <NumericRangeFilter fieldName="age" lowerTerm="20" upperTerm="25"/>
               </Filter>	
            </FilteredQuery>
	         

<NumericRangeFilter>'s attributes
Name	Values	Default
fieldName
includeLower	true, false	true
includeUpper	true, false	true
lowerTerm
precisionStep		4
type	int, long, float, double	int
upperTerm

This element is always empty.

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

The lower-most term value for this field (must be <= upperTerm and a valid native java numeric type)

Required

The upper-most term value for this field (must be >= lowerTerm and a valid native java numeric type)

Required

The numeric type of this field

Possible values: int, long, float, double - Default value: int

Controls if the lowerTerm in the range is part of the allowed set of values

Possible values: true, false - Default value: true

Controls if the upperTerm in the range is part of the allowed set of values

Possible values: true, false - Default value: true

Lower step values mean more precisions and so more terms in index (and index gets larger). This value must be an integer

Default value: 4

A single term used in a SpanQuery. These clauses are the building blocks for more complex "span" queries which test word proximity

Example: Find documents using terms close to each other about mining and accidents

	      <SpanNear slop="8" inOrder="false" fieldName="text">		
			<SpanOr>
				<SpanTerm>killed</SpanTerm>
				<SpanTerm>died</SpanTerm>
				<SpanTerm>dead</SpanTerm>
			</SpanOr>
			<SpanOr>
				<SpanTerm>miner</SpanTerm>
				<SpanTerm>mining</SpanTerm>
				<SpanTerm>miners</SpanTerm>
			</SpanOr>
	      </SpanNear>
	      

<SpanTerm>'s attributes Name Values Default fieldName

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

Required

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

Example: Use SpanOrTerms as a more convenient/succinct way of expressing multiple choices of SpanTerms. This example looks for reports using words describing a fatality near to references to miners

	      <SpanNear slop="8" inOrder="false" fieldName="text">		
			<SpanOrTerms>killed died death dead deaths</SpanOrTerms>
			<SpanOrTerms>miner mining miners</SpanOrTerms>
	      </SpanNear>
	      

<SpanOrTerms>'s attributes Name Values Default fieldName

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

Required

Takes any number of child queries from the Span family

Example: Find documents using terms close to each other about mining and accidents

	      <SpanNear slop="8" inOrder="false" fieldName="text">		
			<SpanOr>
				<SpanTerm>killed</SpanTerm>
				<SpanTerm>died</SpanTerm>
				<SpanTerm>dead</SpanTerm>
			</SpanOr>
			<SpanOr>
				<SpanTerm>miner</SpanTerm>
				<SpanTerm>mining</SpanTerm>
				<SpanTerm>miners</SpanTerm>
			</SpanOr>
	      </SpanNear>
	      

<SpanOr>'s children Name Cardinality BoostingTermQuery Any number SpanFirst Any number SpanNear Any number SpanNot Any number SpanOr Any number SpanOrTerms Any number SpanTerm Any number

(SpanOr | SpanNear | SpanOrTerms | SpanFirst | SpanNot | SpanTerm | BoostingTermQuery)*

Takes any number of child queries from the Span family and tests for proximity

<SpanNear>'s children Name Cardinality BoostingTermQuery Any number SpanFirst Any number SpanNear Any number SpanNot Any number SpanOr Any number SpanOrTerms Any number SpanTerm Any number

<SpanNear>'s attributes Name Values Default inOrder true, false true slop

(SpanOr | SpanNear | SpanOrTerms | SpanFirst | SpanNot | SpanTerm | BoostingTermQuery)*

defines the maximum distance between Span elements where distance is expressed as word number, not byte offset

Example: Find documents using terms within 8 words of each other talking about mining and accidents

	      <SpanNear slop="8" inOrder="false" fieldName="text">		
			<SpanOr>
				<SpanTerm>killed</SpanTerm>
				<SpanTerm>died</SpanTerm>
				<SpanTerm>dead</SpanTerm>
			</SpanOr>
			<SpanOr>
				<SpanTerm>miner</SpanTerm>
				<SpanTerm>mining</SpanTerm>
				<SpanTerm>miners</SpanTerm>
			</SpanOr>
	      </SpanNear>
	      

Required

Controls if matching terms have to appear in the order listed or can be reversed

Possible values: true, false - Default value: true

Looks for a SpanQuery match occuring near the beginning of a document

Example: Find letters where the first 50 words talk about a resignation:

	          
	         <SpanFirst end="50">
	               <SpanOrTerms fieldName="text">resigning resign leave</SpanOrTerms>
	         </SpanFirst>
	         

<SpanFirst>'s children Name Cardinality BoostingTermQuery One or none SpanFirst One or none SpanNear One or none SpanNot One or none SpanOr One or none SpanOrTerms One or none SpanTerm One or none

<SpanFirst>'s attributes Name Values Default boost 1.0 end

(SpanOr | SpanNear | SpanOrTerms | SpanFirst | SpanNot | SpanTerm | BoostingTermQuery)

Controls the end of the region considered in a document's field (expressed in word number, not byte offset)

Required

Optional boost for matches on this query. Values > 1

Default value: 1.0

Finds documents matching a SpanQuery but not if matching another SpanQuery

Example: Find documents talking about social services but not containing the word "public"

          <SpanNot fieldName="text">
             <Include>
                <SpanNear slop="2" inOrder="true">		
                     <SpanTerm>social</SpanTerm>
                     <SpanTerm>services</SpanTerm>
                </SpanNear>				
             </Include>
             <Exclude>
                <SpanTerm>public</SpanTerm>
             </Exclude>
          </SpanNot>
	      

<SpanNot>'s children Name Cardinality Exclude Only one Include Only one

(Include, Exclude)

The SpanQuery to find

<Include>'s children Name Cardinality BoostingTermQuery One or none SpanFirst One or none SpanNear One or none SpanNot One or none SpanOr One or none SpanOrTerms One or none SpanTerm One or none

(SpanOr | SpanNear | SpanOrTerms | SpanFirst | SpanNot | SpanTerm | BoostingTermQuery)

The SpanQuery to be avoided

<Exclude>'s children Name Cardinality BoostingTermQuery One or none SpanFirst One or none SpanNear One or none SpanNot One or none SpanOr One or none SpanOrTerms One or none SpanTerm One or none

(SpanOr | SpanNear | SpanOrTerms | SpanFirst | SpanNot | SpanTerm | BoostingTermQuery)

a utility tag to wrap any filter as a query

Example: Find all documents from the last 10 years

     <ConstantScoreQuery>
           <RangeFilter fieldName="date" lowerTerm="19970101" upperTerm="20070101"/>
     </ConstantScoreQuery>	
	

<ConstantScoreQuery>'s children Name Cardinality BooleanFilter Any number CachedFilter Any number DuplicateFilter Any number NumericRangeFilter Any number RangeFilter Any number TermsFilter Any number

<ConstantScoreQuery>'s attributes Name Values Default boost 1.0

(RangeFilter | NumericRangeFilter | CachedFilter | TermsFilter | BooleanFilter | DuplicateFilter)*

Optional boost for matches on this query. Values > 1

Default value: 1.0

Performs fuzzy matching on "significant" terms in fields. Improves on "LikeThisQuery" by allowing for fuzzy variations of supplied fields. Improves on FuzzyQuery by rewarding all fuzzy variants of a term with the same IDF rather than default fuzzy behaviour which ranks rarer variants (typically misspellings) more highly. This can be a useful default search mode for processing user input where the end user is not expected to know about the standard query operators for fuzzy, boolean or phrase logic found in UserQuery

Example: Search for information about the Sumitomo bank, where the end user has mis-spelt the name

	          
            <FuzzyLikeThisQuery>
                <Field fieldName="contents">
		             Sumitimo bank
	            </Field>
            </FuzzyLikeThisQuery>
	         

<FuzzyLikeThisQuery>'s children Name Cardinality Field Any number

<FuzzyLikeThisQuery>'s attributes Name Values Default boost 1.0 ignoreTF true, false false maxNumTerms 50

(Field)*

Optional boost for matches on this query. Values > 1

Default value: 1.0

Limits the total number of terms selected from the provided text plus the selected "fuzzy" variants

Default value: 50

Ignore "Term Frequency" - a boost factor which rewards multiple occurences of the same term in a document

Possible values: true, false - Default value: false

A field used in a FuzzyLikeThisQuery

<Field>'s attributes Name Values Default fieldName minSimilarity 0.5 prefixLength 1

Controls the level of similarity required for fuzzy variants where 1 is identical and 0.5 is that the variant contains half of the original's characters in the same order. Lower values produce more results but may take longer to execute due to additional IO required to read matching document ids

Default value: 0.5

Controls the minimum number of characters at the start of fuzzy variant words that must exactly match the original. A value of zero will require no minimum and the search software will effectively scan ALL terms from a to z looking for variations. This can incur high CPU overhead and a prefix length of just "1" will reduce this overhead to 1/26th of the original cost (assuming an even distribution of letters used from the alphabet).

Default value: 1

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

Cherry-picks "significant" terms from the example child text and queries using these words. By only using significant (read: rare) terms the performance cost of the query is substantially reduced and large bodies of text can be used as example content.

Example: Use a block of text as an example of the type of content to be found, ignoring the "Reuters" word which appears commonly in the index.

            <LikeThisQuery percentTermsToMatch="5" stopWords="Reuters">
                IRAQI TROOPS REPORTED PUSHING BACK IRANIANS Iraq said today its troops were pushing Iranian forces out of 
                positions they had initially occupied when they launched a new offensive near the southern port of 
                Basra early yesterday.     A High Command communique said Iraqi troops had won a significant victory 
                and were continuing to advance.     Iraq said it had foiled a three-pronged thrust some 10 km 
                (six miles) from Basra, but admitted the Iranians had occupied ground held by the Mohammed al-Qassem 
                unit, one of three divisions attacked.     The communique said Iranian Revolutionary Guards were under 
                assault from warplanes, helicopter gunships, heavy artillery and tanks.     "Our forces are continuing 
                their advance until they purge the last foothold" occupied by the Iranians, it said.     
                (Iran said its troops had killed or wounded more than 4,000 Iraqis and were stabilising their new positions.)     
                The Baghdad communique said Iraqi planes also destroyed oil installations at Iran's southwestern Ahvaz field 
                during a raid today. It denied an Iranian report that an Iraqi jet was shot down.     
                Iraq also reported a naval battle at the northern tip of the Gulf. Iraqi naval units and forces defending an 
                offshore terminal sank six Iranian out of 28 Iranian boats attempting to attack an offshore terminal, 
                the communique said.      Reuters 3;
            </LikeThisQuery>	         
	        

<LikeThisQuery>'s attributes Name Values Default boost 1.0 fieldNames maxQueryTerms 20 minTermFrequency 1 percentTermsToMatch 30 stopWords

Optional boost for matches on this query. Values > 1

Default value: 1.0

Comma delimited list of field names

a list of stop words - analyzed to produce stop terms

controls the maximum number of words shortlisted for the query. The higher the number the slower the response due to more disk reads required

Default value: 20

Controls how many times a term must appear in the example text before it is shortlisted for use in the query

Default value: 1

A quality control that can be used to limit the number of results to those documents matching a certain percentage of the shortlisted query terms. Values must be between 1 and 100

Default value: 30

Requires matches on the "Query" element and optionally boosts by any matches on the "BoostQuery". Unlike a regular BooleanQuery the boost can be less than 1 to produce a subtractive rather than additive result on the match score.

Example: Find documents about banks, preferably related to mergers, and preferably not about "World bank"

	<BoostingQuery>
      <Query>
         <BooleanQuery fieldName="contents">
           <Clause occurs="should">
              <TermQuery>merger</TermQuery>
           </Clause>
           <Clause occurs="must">
              <TermQuery>bank</TermQuery>
           </Clause>
         </BooleanQuery>	
      </Query>
      <BoostQuery boost="0.01">
         <UserQuery>"world bank"</UserQuery>
      </BoostQuery>
    </BoostingQuery>
	

<BoostingQuery>'s children Name Cardinality BoostQuery Only one Query Only one

<BoostingQuery>'s attributes Name Values Default boost 1.0

(Query, BoostQuery)

Optional boost for matches on this query. Values > 1

Default value: 1.0

Child element of BoostingQuery used to contain the choice of Query which is used for boosting purposes

<BoostQuery>'s children Name Cardinality BooleanQuery One or none BoostingQuery One or none BoostingTermQuery One or none ConstantScoreQuery One or none FilteredQuery One or none FuzzyLikeThisQuery One or none LikeThisQuery One or none MatchAllDocsQuery One or none NumericRangeQuery One or none SpanFirst One or none SpanNear One or none SpanNot One or none SpanOr One or none SpanOrTerms One or none SpanTerm One or none TermQuery One or none TermsQuery One or none UserQuery One or none

<BoostQuery>'s attributes Name Values Default boost 1.0

(BooleanQuery | UserQuery | FilteredQuery | TermQuery | TermsQuery | MatchAllDocsQuery | ConstantScoreQuery | BoostingTermQuery | NumericRangeQuery | SpanOr | SpanNear | SpanOrTerms | SpanFirst | SpanNot | SpanTerm | BoostingTermQuery | LikeThisQuery | BoostingQuery | FuzzyLikeThisQuery)

Optional boost for matches on this query. A boost of >0 but <1 effectively demotes results from Query that match this BoostQuery.

Default value: 1.0

Removes duplicated documents from results where "duplicate" means documents share a value for a particular field such as a primary key

Example: Find the latest version of each web page that mentions "Lucene"

    <FilteredQuery>
      <Query>
         <TermQuery fieldName="text">lucene</TermQuery>
      </Query>
	  <Filter>
		<DuplicateFilter fieldName="url" keepMode="last"/>
	  </Filter>	
    </FilteredQuery>	
	

<DuplicateFilter>'s attributes
Name	Values	Default
fieldName
keepMode	first, last	first
processingMode	full, fast	full

This element is always empty.

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

Determines if the first or last document occurence is the one to return when presented with duplicated field values

Possible values: first, last - Default value: first

Controls the choice of process used to produce the filter - "full" mode identifies only non-duplicate documents with the chosen field while "fast" mode may perform faster but will also mark documents without the field as valid. The former approach starts by assuming every document is a duplicate then finds the "master" documents to keep while the latter approach assumes all documents are unique and unmarks those documents that are a copy.

Possible values: full, fast - Default value: full

Processes child text using a field-specific choice of Analyzer to produce a set of terms that are then used as a filter.

Example: Find documents talking about Lucene written on a Monday or a Friday

    <FilteredQuery>
      <Query>
         <TermQuery fieldName="text">lucene</TermQuery>
      </Query>
	<Filter>
		<TermsFilter fieldName="dayOfWeek">monday friday</TermsFilter> 
	</Filter>	
    </FilteredQuery>	
	

<TermsFilter>'s attributes Name Values Default fieldName

fieldName must be defined here or is taken from the most immediate parent XML element that defines a "fieldName" attribute

A Filter equivalent to BooleanQuery that applies Boolean logic to Clauses containing Filters. Unlike BooleanQuery a BooleanFilter can contain a single "mustNot" clause.

Example: Find documents from the first quarter of this year or last year that are not in "draft" status

     <FilteredQuery>
       <Query>
           <MatchAllDocsQuery/>
       </Query>
       <Filter>
        <BooleanFilter>
          <Clause occurs="should">
             <RangeFilter fieldName="date" lowerTerm="20070101" upperTerm="20070401"/>
          </Clause>
          <Clause occurs="should">
             <RangeFilter fieldName="date" lowerTerm="20060101" upperTerm="20060401"/>
          </Clause>
          <Clause occurs="mustNot">
             <TermsFilter fieldName="status">draft</TermsFilter> 
          </Clause>
        </BooleanFilter>
       </Filter>
    </FilteredQuery>
	

<BooleanFilter>'s children Name Cardinality Clause At least one

(Clause)+