org.apache.lucene.search

Interface Searchable

All Superinterfaces:

java.rmi.Remote

All Known Implementing Classes:

IndexSearcher, MultiSearcher, ParallelMultiSearcher, RemoteSearchable, Searcher

public interface Searchable
extends java.rmi.Remote

The interface for search implementations.

Searchable is the abstract network protocol for searching. Implementations provide search over a single index, over multiple indices, and over indices on remote servers.

Queries, filters and sort criteria are designed to be compact so that they may be efficiently passed to a remote index, with only the top-scoring hits being returned, rather than every non-zero scoring hit.

Method Summary

Modifier and Type	Method and Description
void	close() Frees resources associated with this Searcher.
Document	doc(int i) Expert: 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.
int[]	docFreqs(Term[] terms) Expert: For each term in the terms array, calculates 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.
int	maxDoc() Expert: Returns one greater than the largest possible document number.
Query	rewrite(Query query) Expert: called to re-write queries into primitive queries.
void	search(Weight weight, Filter filter, HitCollector results) Lower-level search API.
TopDocs	search(Weight weight, Filter filter, int n) Expert: Low-level search implementation.
TopFieldDocs	search(Weight weight, Filter filter, int n, Sort sort) Expert: Low-level search implementation with arbitrary sorting.

Method Detail

search

void search(Weight weight,
            Filter filter,
            HitCollector results)
     throws java.io.IOException

Lower-level search API.

HitCollector.collect(int,float) is called for every non-zero scoring document.
HitCollector-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)) is usually more efficient, as it skips non-high-scoring hits.

Parameters:

weight - to match documents

filter - if non-null, a bitset used to eliminate some documents

results - to receive hits

Throws:

BooleanQuery.TooManyClauses

java.io.IOException

close

void close()
    throws java.io.IOException

Frees resources associated with this Searcher. Be careful not to call this method while you are still using objects like Hits.

Throws:

java.io.IOException

docFreq

int docFreq(Term term)
     throws java.io.IOException

Expert: Returns the number of documents containing term. Called by search code to compute term weights.

Throws:

java.io.IOException

See Also:

IndexReader.docFreq(Term)

docFreqs

int[] docFreqs(Term[] terms)
        throws java.io.IOException

Expert: For each term in the terms array, calculates the number of documents containing term. Returns an array with these document frequencies. Used to minimize number of remote calls.

Throws:

java.io.IOException

maxDoc

int maxDoc()
    throws java.io.IOException

Expert: Returns one greater than the largest possible document number. Called by search code to compute term weights.

Throws:

java.io.IOException

See Also:

IndexReader.maxDoc()

search

TopDocs search(Weight weight,
               Filter filter,
               int n)
        throws java.io.IOException

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

Called by Hits.

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

Throws:

BooleanQuery.TooManyClauses

java.io.IOException

doc

Document doc(int i)
      throws CorruptIndexException,
             java.io.IOException

Expert: Returns the stored fields of document i. Called by HitCollector implementations.

Throws:

CorruptIndexException - if the index is corrupt

java.io.IOException - if there is a low-level IO error

See Also:

IndexReader.document(int)

doc

Document doc(int n,
             FieldSelector fieldSelector)
      throws CorruptIndexException,
             java.io.IOException

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.

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

java.io.IOException - if there is a low-level IO error

See Also:

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

rewrite

Query rewrite(Query query)
       throws java.io.IOException

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

Throws:

BooleanQuery.TooManyClauses

java.io.IOException

explain

Explanation explain(Weight weight,
                    int doc)
             throws java.io.IOException

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).

Throws:

BooleanQuery.TooManyClauses

java.io.IOException

search

TopFieldDocs search(Weight weight,
                    Filter filter,
                    int n,
                    Sort sort)
             throws java.io.IOException

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,Sort) instead.

Throws:

BooleanQuery.TooManyClauses

java.io.IOException