public class BlockGroupingCollector extends SimpleCollector
IndexWriter.addDocuments()
or IndexWriter.updateDocuments()
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
AllGroupsCollector
. 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 and Description |
---|
BlockGroupingCollector(Sort groupSort,
int topNGroups,
boolean needsScores,
Weight lastDocPerGroup)
Create the single pass collector.
|
Modifier and Type | Method and Description |
---|---|
void |
collect(int doc) |
protected void |
doSetNextReader(LeafReaderContext readerContext) |
TopGroups<?> |
getTopGroups(Sort withinGroupSort,
int groupOffset,
int withinGroupOffset,
int maxDocsPerGroup,
boolean fillSortFields)
Returns the grouped results.
|
boolean |
needsScores() |
void |
setScorer(Scorer scorer) |
getLeafCollector
public BlockGroupingCollector(Sort groupSort, int topNGroups, boolean needsScores, Weight lastDocPerGroup)
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 Weight
that marks the
last document in each group.public TopGroups<?> getTopGroups(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 DocValues, etc.)
withinGroupSort
- The Sort
used to sort
documents within each group.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 setIOException
public void setScorer(Scorer scorer) throws IOException
setScorer
in interface LeafCollector
setScorer
in class SimpleCollector
IOException
public void collect(int doc) throws IOException
collect
in interface LeafCollector
collect
in class SimpleCollector
IOException
protected void doSetNextReader(LeafReaderContext readerContext) throws IOException
doSetNextReader
in class SimpleCollector
IOException
public boolean needsScores()
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