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java.lang.Object org.apache.lucene.search.Collector org.apache.lucene.search.grouping.BlockGroupingCollector
public class BlockGroupingCollector
BlockGroupingCollector performs grouping with a
single pass collector, as long as you are grouping by a
doc block field, ie all documents sharing a given group
value were indexed as a doc block using the atomic
IndexWriter.addDocuments(java.util.Collection
or IndexWriter.updateDocuments(org.apache.lucene.index.Term, java.util.Collection
API.
This results in faster performance (~25% faster QPS)
than the two-pass grouping collectors, with the tradeoff
being that the documents in each group must always be
indexed as a block. This collector also fills in
TopGroups.totalGroupCount without requiring the separate
TermAllGroupsCollector
. However, this collector does
not fill in the groupValue of each group; this field
will always be null.
NOTE: this collector makes no effort to verify the docs were in fact indexed as a block, so it's up to you to ensure this was the case.
See org.apache.lucene.search.grouping
for more
details including a full code example.
Constructor Summary | |
---|---|
BlockGroupingCollector(org.apache.lucene.search.Sort groupSort,
int topNGroups,
boolean needsScores,
org.apache.lucene.search.Filter lastDocPerGroup)
Create the single pass collector. |
Method Summary | |
---|---|
boolean |
acceptsDocsOutOfOrder()
|
void |
collect(int doc)
|
TopGroups |
getTopGroups(org.apache.lucene.search.Sort withinGroupSort,
int groupOffset,
int withinGroupOffset,
int maxDocsPerGroup,
boolean fillSortFields)
Returns the grouped results. |
void |
setNextReader(org.apache.lucene.index.IndexReader reader,
int docBase)
|
void |
setScorer(org.apache.lucene.search.Scorer scorer)
|
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public BlockGroupingCollector(org.apache.lucene.search.Sort groupSort, int topNGroups, boolean needsScores, org.apache.lucene.search.Filter lastDocPerGroup) throws IOException
groupSort
- The Sort
used to sort the
groups. The top sorted document within each group
according to groupSort, determines how that group
sorts against other groups. This must be non-null,
ie, if you want to groupSort by relevance use
Sort.RELEVANCE.topNGroups
- How many top groups to keep.needsScores
- true if the collected documents
require scores, either because relevance is included
in the withinGroupSort or because you plan to pass true
for either getSscores or getMaxScores to getTopGroups(org.apache.lucene.search.Sort, int, int, int, boolean)
lastDocPerGroup
- a Filter
that marks the
last document in each group.
IOException
Method Detail |
---|
public TopGroups getTopGroups(org.apache.lucene.search.Sort withinGroupSort, int groupOffset, int withinGroupOffset, int maxDocsPerGroup, boolean fillSortFields) throws IOException
NOTE: This collector is unable to compute the groupValue per group so it will always be null. This is normally not a problem, as you can obtain the value just like you obtain other values for each matching document (eg, via stored fields, via FieldCache, etc.)
withinGroupSort
- The Sort
used to sort
documents within each group. Passing null is
allowed, to sort by relevance.groupOffset
- Which group to start fromwithinGroupOffset
- Which document to start from
within each groupmaxDocsPerGroup
- How many top documents to keep
within each group.fillSortFields
- If true then the Comparable
values for the sort fields will be set
IOException
public void setScorer(org.apache.lucene.search.Scorer scorer) throws IOException
setScorer
in class org.apache.lucene.search.Collector
IOException
public void collect(int doc) throws IOException
collect
in class org.apache.lucene.search.Collector
IOException
public boolean acceptsDocsOutOfOrder()
acceptsDocsOutOfOrder
in class org.apache.lucene.search.Collector
public void setNextReader(org.apache.lucene.index.IndexReader reader, int docBase) throws IOException
setNextReader
in class org.apache.lucene.search.Collector
IOException
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