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
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 |
---|---|
boolean |
acceptsDocsOutOfOrder()
Return
true if this collector does not
require the matching docIDs to be delivered in int sort
order (smallest to largest) to Collector.collect(int) . |
void |
collect(int parentDoc)
Called once for every document matching a query, with the unbased document
number.
|
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)
Called before collecting from each
AtomicReaderContext . |
void |
setScorer(Scorer scorer)
Called before successive calls to
Collector.collect(int) . |
public ToParentBlockJoinCollector(Sort sort, int numParentHits, boolean trackScores, boolean trackMaxScore) throws IOException
IOException
public void collect(int parentDoc) throws IOException
Collector
Note: The collection of the current segment can be terminated by throwing
a CollectionTerminatedException
. In this case, the last docs of the
current AtomicReaderContext
will be skipped and IndexSearcher
will swallow the exception and continue collection with the next leaf.
Note: This is called in an inner search loop. For good search performance,
implementations of this method should not call IndexSearcher.doc(int)
or
IndexReader.document(int)
on every hit.
Doing so can slow searches by an order of magnitude or more.
collect
in class Collector
IOException
public void setNextReader(AtomicReaderContext context) throws IOException
Collector
AtomicReaderContext
. All doc ids in
Collector.collect(int)
will correspond to IndexReaderContext.reader()
.
Add AtomicReaderContext.docBase
to the current IndexReaderContext.reader()
's
internal document id to re-base ids in Collector.collect(int)
.setNextReader
in class Collector
context
- next atomic reader contextIOException
public boolean acceptsDocsOutOfOrder()
Collector
true
if this collector does not
require the matching docIDs to be delivered in int sort
order (smallest to largest) to Collector.collect(int)
.
Most Lucene Query implementations will visit
matching docIDs in order. However, some queries
(currently limited to certain cases of BooleanQuery
) can achieve faster searching if the
Collector
allows them to deliver the
docIDs out of order.
Many collectors don't mind getting docIDs out of
order, so it's important to return true
here.
acceptsDocsOutOfOrder
in class Collector
public void setScorer(Scorer scorer)
Collector
Collector.collect(int)
. Implementations
that need the score of the current document (passed-in to
Collector.collect(int)
), should save the passed-in Scorer and call
scorer.score() when needed.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
Copyright © 2000-2016 The Apache Software Foundation. All Rights Reserved.