public class ToParentBlockJoinCollector extends Object implements 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.
This collector MUST be used with ToParentBlockJoinIndexSearcher
,
in order to work correctly.
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 and Description |
---|
ToParentBlockJoinCollector(Sort sort,
int numParentHits,
boolean trackScores,
boolean trackMaxScore)
Creates a ToParentBlockJoinCollector.
|
Modifier and Type | Method and Description |
---|---|
LeafCollector |
getLeafCollector(LeafReaderContext context) |
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.
|
boolean |
needsScores() |
public ToParentBlockJoinCollector(Sort sort, int numParentHits, boolean trackScores, boolean trackMaxScore) throws IOException
IOException
public LeafCollector getLeafCollector(LeafReaderContext context) throws IOException
getLeafCollector
in interface Collector
IOException
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 notIOException
- 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 notIOException
- if there is a low-level I/O errorpublic float getMaxScore()
trackMaxScores=true
was passed
on
construction
. Else, this returns Float.NaN
public boolean needsScores()
needsScores
in interface Collector
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