org.apache.lucene.search
Interface Searchable

All Superinterfaces:
Closeable
All Known Implementing Classes:
IndexSearcher, MultiSearcher, ParallelMultiSearcher, Searcher

public interface Searchable
extends Closeable

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 matching hit. NOTE: this interface is kept public for convenience. Since it is not expected to be implemented directly, it may be changed unexpectedly between releases.


Method Summary
 void close()
          Frees resources associated with this Searcher.
 Document doc(int i)
          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, Collector collector)
          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,
            Collector collector)
            throws IOException
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.

Parameters:
weight - to match documents
filter - if non-null, used to permit documents to be collected.
collector - to receive hits
Throws:
BooleanQuery.TooManyClauses
IOException

close

void close()
           throws IOException
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
Throws:
IOException

docFreq

int docFreq(Term term)
            throws IOException
Expert: Returns the number of documents containing term.

Throws:
IOException
See Also:
IndexReader.docFreq(Term)

docFreqs

int[] docFreqs(Term[] terms)
               throws 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:
IOException

maxDoc

int maxDoc()
           throws IOException
Expert: Returns one greater than the largest possible document number.

Throws:
IOException
See Also:
IndexReader.maxDoc()

search

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

Throws:
BooleanQuery.TooManyClauses
IOException

doc

Document doc(int i)
             throws CorruptIndexException,
                    IOException
Returns the stored fields of document i.

Throws:
CorruptIndexException - if the index is corrupt
IOException - if there is a low-level IO error
See Also:
IndexReader.document(int)

doc

Document doc(int n,
             FieldSelector fieldSelector)
             throws CorruptIndexException,
                    IOException
Get the Document at the nth 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 nth 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

rewrite

Query rewrite(Query query)
              throws IOException
Expert: called to re-write queries into primitive queries.

Throws:
BooleanQuery.TooManyClauses
IOException

explain

Explanation explain(Weight weight,
                    int doc)
                    throws 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
IOException

search

TopFieldDocs search(Weight weight,
                    Filter filter,
                    int n,
                    Sort sort)
                    throws 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,int,Sort) instead.

Throws:
BooleanQuery.TooManyClauses
IOException


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