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java.lang.Object org.apache.lucene.search.Collector org.apache.lucene.search.join.ToParentBlockJoinCollector
public class ToParentBlockJoinCollector
Collects parent document hits for a Query containing one more more
BlockJoinQuery clauses, sorted by the
specified parent Sort. Note that this cannot perform
arbitrary joins; rather, it requires that all joined
documents are indexed as a doc block (using 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
a 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 ToParentBlockJoinQuery
's
matching child documents for the top parent groups,
using 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 TopGroups
instances.
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
correct.
See org.apache.lucene.search.join
for a code
sample.
Constructor Summary | |
---|---|
ToParentBlockJoinCollector(Sort sort,
int numParentHits,
boolean trackScores,
boolean trackMaxScore)
Creates a ToParentBlockJoinCollector. |
Method Summary | |
---|---|
boolean |
acceptsDocsOutOfOrder()
|
void |
collect(int parentDoc)
|
float |
getMaxScore()
Returns the highest score across all collected parent hits, as long as trackMaxScores=true was passed
on
construction . |
TopGroups<Integer> |
getTopGroups(ToParentBlockJoinQuery query,
Sort withinGroupSort,
int offset,
int maxDocsPerGroup,
int withinGroupOffset,
boolean fillSortFields)
Returns the TopGroups for the specified BlockJoinQuery. |
TopGroups<Integer> |
getTopGroupsWithAllChildDocs(ToParentBlockJoinQuery query,
Sort withinGroupSort,
int offset,
int withinGroupOffset,
boolean fillSortFields)
Returns the TopGroups for the specified BlockJoinQuery. |
void |
setNextReader(AtomicReaderContext context)
|
void |
setScorer(Scorer scorer)
|
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
---|
public ToParentBlockJoinCollector(Sort sort, int numParentHits, boolean trackScores, boolean trackMaxScore) throws IOException
IOException
Method Detail |
---|
public void collect(int parentDoc) throws IOException
collect
in class Collector
IOException
public void setNextReader(AtomicReaderContext context) throws IOException
setNextReader
in class Collector
IOException
public boolean acceptsDocsOutOfOrder()
acceptsDocsOutOfOrder
in class Collector
public void setScorer(Scorer scorer)
setScorer
in class Collector
public TopGroups<Integer> getTopGroups(ToParentBlockJoinQuery query, Sort withinGroupSort, int offset, int maxDocsPerGroup, int withinGroupOffset, boolean fillSortFields) throws IOException
maxDocsPerGroup
and number of matched child documents for that group.
Returns null if no groups matched.
query
- Search querywithinGroupSort
- Sort criteria within groupsoffset
- Parent docs offsetmaxDocsPerGroup
- Upper bound of documents per group numberwithinGroupOffset
- Offset within each group of child docsfillSortFields
- Specifies whether to add sort fields or not
IOException
- if there is a low-level I/O errorpublic TopGroups<Integer> getTopGroupsWithAllChildDocs(ToParentBlockJoinQuery query, Sort withinGroupSort, int offset, int withinGroupOffset, boolean fillSortFields) throws IOException
query
- Search querywithinGroupSort
- Sort criteria within groupsoffset
- Parent docs offsetwithinGroupOffset
- Offset within each group of child docsfillSortFields
- Specifies whether to add sort fields or not
IOException
- if there is a low-level I/O errorpublic float getMaxScore()
trackMaxScores=true
was passed
on
construction
. Else, this returns Float.NaN
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