org.apache.lucene.search
Class MultiSearcher

java.lang.Object
  org.apache.lucene.search.Searcher
      org.apache.lucene.search.MultiSearcher

All Implemented Interfaces:

Closeable, Searchable

Direct Known Subclasses:

ParallelMultiSearcher

public class MultiSearcher
extends Searcher

Implements search over a set of Searchables.

Applications usually need only call the inherited Searcher.search(Query,int) or Searcher.search(Query,Filter,int) methods.

Constructor Summary

MultiSearcher(Searchable... searchables)
Creates a searcher which searches searchers.

Method Summary

void	close() Frees resources associated with this Searcher.
protected Weight	createWeight(Query original) Create weight in multiple index scenario.
Document	doc(int n) Returns the stored fields of document i.
Document	doc(int n, FieldSelector fieldSelector) Get the Document at the nth position.
int	docFreq(Term term) Expert: Returns the number of documents containing term.
Explanation	explain(Weight weight, int doc) Expert: low-level implementation method Returns an Explanation that describes how doc scored against weight.
Searchable[]	getSearchables() Return the array of Searchables this searches.
protected int[]	getStarts()
int	maxDoc() Expert: Returns one greater than the largest possible document number.
Query	rewrite(Query original) Expert: called to re-write queries into primitive queries.
void	search(Weight weight, Filter filter, Collector collector) Lower-level search API.
TopDocs	search(Weight weight, Filter filter, int nDocs) Expert: Low-level search implementation.
TopFieldDocs	search(Weight weight, Filter filter, int n, Sort sort) Expert: Low-level search implementation with arbitrary sorting.
int	subDoc(int n) Returns the document number of document n within its sub-index.
int	subSearcher(int n) Returns index of the searcher for document n in the array used to construct this searcher.

Methods inherited from class org.apache.lucene.search.Searcher

docFreqs, explain, getSimilarity, search, search, search, search, search, setSimilarity

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MultiSearcher

public MultiSearcher(Searchable... searchables)
              throws IOException

Creates a searcher which searches searchers.

Throws:

IOException

Method Detail

getSearchables

public Searchable[] getSearchables()

Return the array of Searchables this searches.

getStarts

protected int[] getStarts()

close

public void close()
           throws IOException

Description copied from interface: Searchable

Frees resources associated with this Searcher. Be careful not to call this method while you are still using objects that reference this Searchable.

Specified by:

close in interface Closeable

Specified by:

close in interface Searchable

Specified by:

close in class Searcher

Throws:

IOException

docFreq

public int docFreq(Term term)
            throws IOException

Description copied from interface: Searchable

Expert: Returns the number of documents containing term.

Specified by:

docFreq in interface Searchable

Specified by:

docFreq in class Searcher

Throws:

IOException

See Also:

IndexReader.docFreq(Term)

doc

public Document doc(int n)
             throws CorruptIndexException,
                    IOException

Description copied from interface: Searchable

Returns the stored fields of document i.

Specified by:

doc in interface Searchable

Specified by:

doc in class Searcher

Throws:

CorruptIndexException - if the index is corrupt

IOException - if there is a low-level IO error

See Also:

IndexReader.document(int)

doc

public Document doc(int n,
                    FieldSelector fieldSelector)
             throws CorruptIndexException,
                    IOException

Description copied from interface: Searchable

Get the Document at the n^th position. The FieldSelector may be used to determine what Fields to load and how they should be loaded. NOTE: If the underlying Reader (more specifically, the underlying FieldsReader) is closed before the lazy Field is loaded an exception may be thrown. If you want the value of a lazy Field to be available after closing you must explicitly load it or fetch the Document again with a new loader.

Specified by:

doc in interface Searchable

Specified by:

doc in class Searcher

Parameters:

n - Get the document at the n^th position

fieldSelector - The FieldSelector to use to determine what Fields should be loaded on the Document. May be null, in which case all Fields will be loaded.

Returns:

The stored fields of the Document at the nth position

Throws:

CorruptIndexException - if the index is corrupt

IOException - if there is a low-level IO error

See Also:

IndexReader.document(int, FieldSelector), Fieldable, FieldSelector, SetBasedFieldSelector, LoadFirstFieldSelector

subSearcher

public int subSearcher(int n)

Returns index of the searcher for document n in the array used to construct this searcher.

subDoc

public int subDoc(int n)

Returns the document number of document n within its sub-index.

maxDoc

public int maxDoc()
           throws IOException

Description copied from interface: Searchable

Expert: Returns one greater than the largest possible document number.

Specified by:

maxDoc in interface Searchable

Specified by:

maxDoc in class Searcher

Throws:

IOException

See Also:

IndexReader.maxDoc()

search

public TopDocs search(Weight weight,
                      Filter filter,
                      int nDocs)
               throws IOException

Description copied from interface: Searchable

Expert: Low-level search implementation. Finds the top n hits for query, applying filter if non-null.

Applications should usually call Searcher.search(Query,int) or Searcher.search(Query,Filter,int) instead.

Specified by:

search in interface Searchable

Specified by:

search in class Searcher

Throws:

IOException

search

public TopFieldDocs search(Weight weight,
                           Filter filter,
                           int n,
                           Sort sort)
                    throws IOException

Description copied from interface: Searchable

Expert: Low-level search implementation with arbitrary sorting. Finds the top n hits for query, applying filter if non-null, and sorting the hits by the criteria in sort.

Applications should usually call Searcher.search(Query,Filter,int,Sort) instead.

Specified by:

search in interface Searchable

Specified by:

search in class Searcher

Throws:

IOException

search

public void search(Weight weight,
                   Filter filter,
                   Collector collector)
            throws IOException

Description copied from interface: Searchable

Lower-level search API.

Collector.collect(int) is called for every document.
Collector-based access to remote indexes is discouraged.

Applications should only use this if they need all of the matching documents. The high-level search API (Searcher.search(Query,int)) is usually more efficient, as it skips non-high-scoring hits.

Specified by:

search in interface Searchable

Specified by:

search in class Searcher

Parameters:

weight - to match documents

filter - if non-null, used to permit documents to be collected.

collector - to receive hits

Throws:

IOException

rewrite

public Query rewrite(Query original)
              throws IOException

Description copied from interface: Searchable

Expert: called to re-write queries into primitive queries.

Specified by:

rewrite in interface Searchable

Specified by:

rewrite in class Searcher

Throws:

IOException

explain

public Explanation explain(Weight weight,
                           int doc)
                    throws IOException

Description copied from interface: Searchable

Expert: low-level implementation method Returns an Explanation that describes how doc scored against weight.

This is intended to be used in developing Similarity implementations, and, for good performance, should not be displayed with every hit. Computing an explanation is as expensive as executing the query over the entire index.

Applications should call Searcher.explain(Query, int).

Specified by:

explain in interface Searchable

Specified by:

explain in class Searcher

Throws:

IOException

createWeight

protected Weight createWeight(Query original)
                       throws IOException

Create weight in multiple index scenario. Distributed query processing is done in the following steps: 1. rewrite query 2. extract necessary terms 3. collect dfs for these terms from the Searchables 4. create query weight using aggregate dfs. 5. distribute that weight to Searchables 6. merge results Steps 1-4 are done here, 5+6 in the search() methods

Overrides:

createWeight in class Searcher

Returns:

rewritten queries

Throws:

IOException