org.apache.lucene.search.join

Class ToParentBlockJoinQuery

java.lang.Object

org.apache.lucene.search.Query

org.apache.lucene.search.join.ToParentBlockJoinQuery

public class ToParentBlockJoinQuery
extends Query

This query requires that you index children and parent docs as a single block, using the IndexWriter.addDocuments() or IndexWriter.updateDocuments() API. In each block, the child documents must appear first, ending with the parent document. At search time you provide a Filter identifying the parents, however this Filter must provide an BitSet per sub-reader.

Once the block index is built, use this query to wrap any sub-query matching only child docs and join matches in that child document space up to the parent document space. You can then use this Query as a clause with other queries in the parent document space.

See ToChildBlockJoinQuery if you need to join in the reverse order.

The child documents must be orthogonal to the parent documents: the wrapped child query must never return a parent document.

See org.apache.lucene.search.join for an overview.

Constructor Summary

Constructors

Constructor and Description
ToParentBlockJoinQuery(Query childQuery, BitSetProducer parentsFilter, ScoreMode scoreMode) Create a ToParentBlockJoinQuery.

Method Summary

Modifier and Type	Method and Description
Weight	createWeight(IndexSearcher searcher, boolean needsScores, float boost) Expert: Constructs an appropriate Weight implementation for this query.
boolean	equals(java.lang.Object other) Override and implement query instance equivalence properly in a subclass.
Query	getChildQuery() Return our child query.
int	hashCode() Override and implement query hash code properly in a subclass.
Query	rewrite(IndexReader reader) Expert: called to re-write queries into primitive queries.
java.lang.String	toString(java.lang.String field) Prints a query to a string, with field assumed to be the default field and omitted.

Methods inherited from class org.apache.lucene.search.Query

classHash, sameClassAs, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ToParentBlockJoinQuery

public ToParentBlockJoinQuery(Query childQuery,
                              BitSetProducer parentsFilter,
                              ScoreMode scoreMode)

Create a ToParentBlockJoinQuery.

Parameters:

childQuery - Query matching child documents.

parentsFilter - Filter identifying the parent documents.

scoreMode - How to aggregate multiple child scores into a single parent score.

Method Detail

createWeight

public Weight createWeight(IndexSearcher searcher,
                           boolean needsScores,
                           float boost)
                    throws java.io.IOException

Description copied from class: Query

Expert: Constructs an appropriate Weight implementation for this query.

Only implemented by primitive queries, which re-write to themselves.

Overrides:

createWeight in class Query

needsScores - True if document scores (Scorer.score()) are needed.

boost - The boost that is propagated by the parent queries.

Throws:

java.io.IOException

getChildQuery

public Query getChildQuery()

Return our child query.

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

toString

public java.lang.String toString(java.lang.String field)

Description copied from class: Query

Prints a query to a string, with field assumed to be the default field and omitted.

Specified by:

toString in class Query

equals

public boolean equals(java.lang.Object other)

Description copied from class: Query

Override and implement query instance equivalence properly in a subclass. This is required so that QueryCache works properly. Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.

Specified by:

equals in class Query

See Also:

Query.sameClassAs(Object), Query.classHash()

hashCode

public int hashCode()

Description copied from class: Query

Override and implement query hash code properly in a subclass. This is required so that QueryCache works properly.

Specified by:

hashCode in class Query

See Also:

Query.equals(Object)