Documentation of 'org.apache.lucene.search.BooleanQuery' Java class
BooleanQuery
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org.apache.lucene.search

Class BooleanQuery

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Cloneable

    public class BooleanQuery
extends Query
    A Query that matches documents matching boolean combinations of other queries, e.g. TermQuerys, PhraseQuerys or other BooleanQuerys.
    See Also:
    Serialized Form

    • Constructor Detail

      • BooleanQuery

        public BooleanQuery()
        Constructs an empty boolean query.

      • BooleanQuery

        public BooleanQuery(boolean disableCoord)
        Constructs an empty boolean query. Similarity.coord(int,int) may be disabled in scoring, as appropriate. For example, this score factor does not make sense for most automatically generated queries, like WildcardQuery and FuzzyQuery.
        Parameters:
        disableCoord - disables Similarity.coord(int,int) in scoring.

    • Method Detail

      • getMaxClauseCount

        public static int getMaxClauseCount()
        Return the maximum number of clauses permitted, 1024 by default. Attempts to add more than the permitted number of clauses cause BooleanQuery.TooManyClauses to be thrown.
        See Also:
        setMaxClauseCount(int)

      • setMaxClauseCount

        public static void setMaxClauseCount(int maxClauseCount)
        Set the maximum number of clauses permitted per BooleanQuery. Default value is 1024.

        TermQuery clauses are generated from for example prefix queries and fuzzy queries. Each TermQuery needs some buffer space during search, so this parameter indirectly controls the maximum buffer requirements for query search.

        When this parameter becomes a bottleneck for a Query one can use a Filter. For example instead of a RangeQuery one can use a RangeFilter.

        Normally the buffers are allocated by the JVM. When using for example MMapDirectory the buffering is left to the operating system.

      • getSimilarity

        public Similarity getSimilarity(Searcher searcher)
        Description copied from class: Query
        Expert: Returns the Similarity implementation to be used for this query. Subclasses may override this method to specify their own Similarity implementation, perhaps one that delegates through that of the Searcher. By default the Searcher's Similarity implementation is returned.
        Overrides:
        getSimilarity in class Query

      • setMinimumNumberShouldMatch

        public void setMinimumNumberShouldMatch(int min)
        Specifies a minimum number of the optional BooleanClauses which must be satisfied.

        By default no optional clauses are necessary for a match (unless there are no required clauses). If this method is used, then the specified number of clauses is required.

        Use of this method is totally independent of specifying that any specific clauses are required (or prohibited). This number will only be compared against the number of matching optional clauses.

        EXPERT NOTE: Using this method may force collecting docs in order, regardless of whether setAllowDocsOutOfOrder(true) has been called.

        Parameters:
        min - the number of optional clauses that must match
        See Also:
        setAllowDocsOutOfOrder(boolean)

      • getMinimumNumberShouldMatch

        public int getMinimumNumberShouldMatch()
        Gets the minimum number of the optional BooleanClauses which must be satisifed.

      • getClauses

        public BooleanClause[] getClauses()
        Returns the set of clauses in this query.

      • clauses

        public java.util.List clauses()
        Returns the list of clauses in this query.

      • setAllowDocsOutOfOrder

        public static void setAllowDocsOutOfOrder(boolean allow)
        Expert: Indicates whether hit docs may be collected out of docid order.

        Background: although the contract of the Scorer class requires that documents be iterated in order of doc id, this was not true in early versions of Lucene. Many pieces of functionality in the current Lucene code base have undefined behavior if this contract is not upheld, but in some specific simple cases may be faster. (For example: disjunction queries with less than 32 prohibited clauses; This setting has no effect for other queries.)

        Specifics: By setting this option to true, calls to HitCollector.collect(int,float) might be invoked first for docid N and only later for docid N-1. Being static, this setting is system wide.

      • getAllowDocsOutOfOrder

        public static boolean getAllowDocsOutOfOrder()
        Whether hit docs may be collected out of docid order.
        See Also:
        setAllowDocsOutOfOrder(boolean)

      • rewrite

        public Query rewrite(IndexReader reader)
              throws java.io.IOException
        Description copied from class: Query
        Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.
        Overrides:
        rewrite in class Query
        Throws:
        java.io.IOException

      • extractTerms

        public void extractTerms(java.util.Set terms)
        Description copied from class: Query
        Expert: adds all terms occuring in this query to the terms set. Only works if this query is in its rewritten form.
        Overrides:
        extractTerms in class Query

      • clone

        public java.lang.Object clone()
        Description copied from class: Query
        Returns a clone of this query.
        Overrides:
        clone in class Query

      • toString

        public java.lang.String toString(java.lang.String field)
        Prints a user-readable version of this query.
        Specified by:
        toString in class Query

      • equals

        public boolean equals(java.lang.Object o)
        Returns true iff o is equal to this.
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public int hashCode()
        Returns a hash code value for this object.
        Overrides:
        hashCode in class java.lang.Object
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