Class ToParentBlockJoinQuery
- java.lang.Object
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- org.apache.lucene.search.Query
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- org.apache.lucene.search.join.ToParentBlockJoinQuery
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- All Implemented Interfaces:
Serializable
,Cloneable
public class ToParentBlockJoinQuery extends Query
This query requires that you index children and parent docs as a single block, using theIndexWriter.addDocuments(java.util.Collection<org.apache.lucene.document.Document>)
orIndexWriter.updateDocuments(org.apache.lucene.index.Term, java.util.Collection<org.apache.lucene.document.Document>)
API. In each block, the child documents must appear first, ending with the parent document. At search time you provide a Filter identifying the parents, however this Filter must provide anFixedBitSet
per sub-reader.WARNING: to create the parents filter, always use
RawTermFilter
(so that the filter includes deleted docs), wrapped withCachingWrapperFilter
(so that the returned bit set per reader is aFixedBitSet
), specifying DeletesMode.IGNORE (so that on reopen, the filter still includes deleted docs). Failure to do this can result in completely wrong documents being returned! For example:Filter parents = new CachingWrapperFilter( new RawTermFilter(new Term("parent", "yes")), CachingWrapperFilter.DeletesMode.IGNORE);
Once the block index is built, use this query to wrap any sub-query matching only child docs and join matches in that child document space up to the parent document space. You can then use this Query as a clause with other queries in the parent document space.
See
ToChildBlockJoinQuery
if you need to join in the reverse order.The child documents must be orthogonal to the parent documents: the wrapped child query must never return a parent document.
If you'd like to retrieveTopGroups
for the resulting query, use theToParentBlockJoinCollector
. Note that this is not necessary, ie, if you simply want to collect the parent documents and don't need to see which child documents matched under that parent, then you can use any collector.NOTE: If the overall query contains parent-only matches, for example you OR a parent-only query with a joined child-only query, then the resulting collected documents will be correct, however the
TopGroups
you get fromToParentBlockJoinCollector
will not contain every child for parents that had matched.See
org.apache.lucene.search.join
for an overview.- See Also:
- Serialized Form
- WARNING: This API is experimental and might change in incompatible ways in the next release.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
ToParentBlockJoinQuery.ScoreMode
How to aggregate multiple child hit scores into a single parent score.
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Constructor Summary
Constructors Constructor Description ToParentBlockJoinQuery(Query childQuery, Filter parentsFilter, ToParentBlockJoinQuery.ScoreMode scoreMode)
Create a ToParentBlockJoinQuery.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description Object
clone()
Returns a clone of this query.Weight
createWeight(Searcher searcher)
Expert: Constructs an appropriate Weight implementation for this query.boolean
equals(Object _other)
void
extractTerms(Set<Term> terms)
Expert: adds all terms occurring in this query to the terms set.int
hashCode()
Query
rewrite(IndexReader reader)
Expert: called to re-write queries into primitive queries.String
toString(String field)
Prints a query to a string, withfield
assumed to be the default field and omitted.-
Methods inherited from class org.apache.lucene.search.Query
combine, getBoost, getSimilarity, mergeBooleanQueries, setBoost, toString, weight
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Constructor Detail
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ToParentBlockJoinQuery
public ToParentBlockJoinQuery(Query childQuery, Filter parentsFilter, ToParentBlockJoinQuery.ScoreMode scoreMode)
Create a ToParentBlockJoinQuery.- Parameters:
childQuery
- Query matching child documents.parentsFilter
- Filter (must produce FixedBitSet per-seegment) identifying the parent documents.scoreMode
- How to aggregate multiple child scores into a single parent score.
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Method Detail
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createWeight
public Weight createWeight(Searcher searcher) throws IOException
Description copied from class:Query
Expert: Constructs an appropriate Weight implementation for this query.Only implemented by primitive queries, which re-write to themselves.
- Overrides:
createWeight
in classQuery
- Throws:
IOException
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extractTerms
public void extractTerms(Set<Term> terms)
Description copied from class:Query
Expert: adds all terms occurring in this query to the terms set. Only works if this query is in itsrewritten
form.- Overrides:
extractTerms
in classQuery
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rewrite
public Query rewrite(IndexReader reader) throws IOException
Description copied from class:Query
Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.- Overrides:
rewrite
in classQuery
- Throws:
IOException
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toString
public String toString(String field)
Description copied from class:Query
Prints a query to a string, withfield
assumed to be the default field and omitted.The representation used is one that is supposed to be readable by
QueryParser
. However, there are the following limitations:- If the query was created by the parser, the printed representation may not be exactly what was parsed. For example, characters that need to be escaped will be represented without the required backslash.
- Some of the more complicated queries (e.g. span queries) don't have a representation that can be parsed by QueryParser.
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