java.lang.Object | ||
↳ | org.apache.lucene.search.Query | |
↳ | org.apache.lucene.search.DisjunctionMaxQuery |
A query that generates the union of documents produced by its subqueries, and that scores each document with the maximum score for that document as produced by any subquery, plus a tie breaking increment for any additional matching subqueries. This is useful when searching for a word in multiple fields with different boost factors (so that the fields cannot be combined equivalently into a single search field). We want the primary score to be the one associated with the highest boost, not the sum of the field scores (as BooleanQuery would give). If the query is "albino elephant" this ensures that "albino" matching one field and "elephant" matching another gets a higher score than "albino" matching both fields. To get this result, use both BooleanQuery and DisjunctionMaxQuery: for each term a DisjunctionMaxQuery searches for it in each field, while the set of these DisjunctionMaxQuery's is combined into a BooleanQuery. The tie breaker capability allows results that include the same term in multiple fields to be judged better than results that include this term in only the best of those multiple fields, without confusing this with the better case of two different terms in the multiple fields.
Nested Classes | |||||||||||
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DisjunctionMaxQuery.DisjunctionMaxWeight | Expert: the Weight for DisjunctionMaxQuery, used to normalize, score and explain these queries. |
Public Constructors | |||||||||||
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Creates a new empty DisjunctionMaxQuery.
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Creates a new DisjunctionMaxQuery
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Public Methods | |||||||||||
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Add a subquery to this disjunction
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Add a collection of disjuncts to this disjunction
via Iterable
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Create a shallow copy of us -- used in rewriting if necessary
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Expert: Constructs an appropriate Weight implementation for this query.
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Return true iff we represent the same query as o
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Expert: adds all terms occurring in this query to the terms set.
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Compute a hash code for hashing us
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An Iterator
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Optimize our representation and our subqueries representations
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Prettyprint us.
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[Expand]
Inherited Methods | |||||||||||
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From class
org.apache.lucene.search.Query
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From class
java.lang.Object
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From interface
java.lang.Iterable
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Creates a new empty DisjunctionMaxQuery. Use add() to add the subqueries.
tieBreakerMultiplier | the score of each non-maximum disjunct for a document is multiplied by this weight and added into the final score. If non-zero, the value should be small, on the order of 0.1, which says that 10 occurrences of word in a lower-scored field that is also in a higher scored field is just as good as a unique word in the lower scored field (i.e., one that is not in any higher scored field. |
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Creates a new DisjunctionMaxQuery
disjuncts | a Collection |
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tieBreakerMultiplier | the weight to give to each matching non-maximum disjunct |
Add a subquery to this disjunction
query | the disjunct added |
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Add a collection of disjuncts to this disjunction
via Iterable
Create a shallow copy of us -- used in rewriting if necessary
Expert: Constructs an appropriate Weight implementation for this query.
Only implemented by primitive queries, which re-write to themselves.
IOException |
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Return true iff we represent the same query as o
o | another object |
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Expert: adds all terms occurring in this query to the terms set. Only
works if this query is in its rewritten
form.
Compute a hash code for hashing us
Optimize our representation and our subqueries representations
reader | the IndexReader we query |
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IOException |
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Prettyprint us.
field | the field to which we are applied |
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