public class ToParentBlockJoinCollector extends Collector
IndexWriter.addDocuments(java.lang.Iterable<? extends java.lang.Iterable<? extends org.apache.lucene.index.IndexableField>>)or
IndexWriter.updateDocuments(org.apache.lucene.index.Term, java.lang.Iterable<? extends java.lang.Iterable<? extends org.apache.lucene.index.IndexableField>>)). Ie, the join is computed at index time.
The parent Sort must only use fields from the parent documents; sorting by field in the child documents is not supported.
You should only use this
collector if one or more of the clauses in the query is
ToParentBlockJoinQuery. This collector will find those query
clauses and record the matching child documents for the
top scoring parent documents.
Multiple joins (star join) and nested joins and a mix of the two are allowed, as long as in all cases the documents corresponding to a single row of each joined parent table were indexed as a doc block.
For the simple star join you can retrieve the
TopGroups instance containing each
matching child documents for the top parent groups,
getTopGroups(org.apache.lucene.search.join.ToParentBlockJoinQuery, org.apache.lucene.search.Sort, int, int, int, boolean). Ie,
a single query, which will contain two or more
ToParentBlockJoinQuery's as clauses representing the star join,
can then retrieve two or more
For nested joins, the query will run correctly (ie,
match the right parent and child documents), however,
because TopGroups is currently unable to support nesting
(each group is not able to hold another TopGroups), you
are only able to retrieve the TopGroups of the first
join. The TopGroups of the nested joins will not be
org.apache.lucene.search.join for a code
|Constructor and Description|
Creates a ToParentBlockJoinCollector.
|Modifier and Type||Method and Description|
Returns the highest score across all collected parent hits, as long as
Return the TopGroups for the specified BlockJoinQuery.
public ToParentBlockJoinCollector(Sort sort, int numParentHits, boolean trackScores, boolean trackMaxScore) throws IOException
public void collect(int parentDoc) throws IOException
public void setNextReader(AtomicReaderContext context) throws IOException
public boolean acceptsDocsOutOfOrder()
public TopGroups<Integer> getTopGroups(ToParentBlockJoinQuery query, Sort withinGroupSort, int offset, int maxDocsPerGroup, int withinGroupOffset, boolean fillSortFields) throws IOException
GroupDocs.totalHits, which would be the total number of child documents matching that parent, is not computed (will always be 0). Returns null if no groups matched.
public float getMaxScore()
on construction. Else, this returns
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