Class ToParentBlockJoinQuery

  extended by
      extended by
All Implemented Interfaces:

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 FixedBitSet 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.

If you'd like to retrieve TopGroups for the resulting query, use the ToParentBlockJoinCollector. Note that this is not necessary, ie, if you simply want to collect the parent documents and don't need to see which child documents matched under that parent, then you can use any collector.

NOTE: If the overall query contains parent-only matches, for example you OR a parent-only query with a joined child-only query, then the resulting collected documents will be correct, however the TopGroups you get from ToParentBlockJoinCollector will not contain every child for parents that had matched.

See for an overview.

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary
ToParentBlockJoinQuery(Query childQuery, Filter parentsFilter, ScoreMode scoreMode)
          Create a ToParentBlockJoinQuery.
Method Summary
 Weight createWeight(IndexSearcher searcher)
 boolean equals(Object _other)
 void extractTerms(Set<Term> terms)
 int hashCode()
 Query rewrite(IndexReader reader)
 String toString(String field)
Methods inherited from class
clone, getBoost, setBoost, toString
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail


public ToParentBlockJoinQuery(Query childQuery,
                              Filter parentsFilter,
                              ScoreMode scoreMode)
Create a ToParentBlockJoinQuery.

childQuery - Query matching child documents.
parentsFilter - Filter (must produce FixedBitSet per-segment, like FixedBitSetCachingWrapperFilter) identifying the parent documents.
scoreMode - How to aggregate multiple child scores into a single parent score.
Method Detail


public Weight createWeight(IndexSearcher searcher)
                    throws IOException
createWeight in class Query


public void extractTerms(Set<Term> terms)
extractTerms in class Query


public Query rewrite(IndexReader reader)
              throws IOException
rewrite in class Query


public String toString(String field)
Specified by:
toString in class Query


public boolean equals(Object _other)
equals in class Query


public int hashCode()
hashCode in class Query

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