org.apache.lucene.index
Class ParallelReader

java.lang.Object
  org.apache.lucene.index.IndexReader
      org.apache.lucene.index.ParallelReader

public class ParallelReader
extends IndexReader

An IndexReader which reads multiple, parallel indexes. Each index added must have the same number of documents, but typically each contains different fields. Each document contains the union of the fields of all documents with the same document number. When searching, matches for a query term are from the first index added that has the field.

This is useful, e.g., with collections that have large fields which change rarely and small fields that change more frequently. The smaller fields may be re-indexed in a new index and both indexes may be searched together.

Warning: It is up to you to make sure all indexes are created and modified the same way. For example, if you add documents to one index, you need to add the same documents in the same order to the other indexes. Failure to do so will result in undefined behavior.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader

IndexReader.FieldOption

Field Summary

Fields inherited from class org.apache.lucene.index.IndexReader

deleter

Constructor Summary

ParallelReader()
Construct a ParallelReader.

Method Summary

void	add(IndexReader reader) Add an IndexReader.
void	add(IndexReader reader, boolean ignoreStoredFields) Add an IndexReader whose stored fields will not be returned.
int	docFreq(Term term) Returns the number of documents containing the term t.
protected void	doClose() Implements close.
protected void	doCommit() Implements commit.
Document	document(int n, FieldSelector fieldSelector) Get the Document at the nth position.
protected void	doDelete(int n) Implements deletion of the document numbered docNum.
protected void	doSetNorm(int n, String field, byte value) Implements setNorm in subclass.
protected void	doUndeleteAll() Implements actual undeleteAll() in subclass.
Collection	getFieldNames(IndexReader.FieldOption fieldNames) Get a list of unique field names that exist in this index and have the specified field option information.
TermFreqVector	getTermFreqVector(int n, String field) Return a term frequency vector for the specified document and field.
TermFreqVector[]	getTermFreqVectors(int n) Return an array of term frequency vectors for the specified document.
boolean	hasDeletions() Returns true if any documents have been deleted
boolean	hasNorms(String field) Returns true if there are norms stored for this field.
boolean	isDeleted(int n) Returns true if document n has been deleted
int	maxDoc() Returns one greater than the largest possible document number.
byte[]	norms(String field) Returns the byte-encoded normalization factor for the named field of every document.
void	norms(String field, byte[] result, int offset) Reads the byte-encoded normalization factor for the named field of every document.
int	numDocs() Returns the number of documents in this index.
TermDocs	termDocs() Returns an unpositioned TermDocs enumerator.
TermDocs	termDocs(Term term) Returns an enumeration of all the documents which contain term.
TermPositions	termPositions() Returns an unpositioned TermPositions enumerator.
TermPositions	termPositions(Term term) Returns an enumeration of all the documents which contain term.
TermEnum	terms() Returns an enumeration of all the terms in the index.
TermEnum	terms(Term term) Returns an enumeration of all terms after a given term.

Methods inherited from class org.apache.lucene.index.IndexReader

close, commit, deleteDocument, deleteDocuments, directory, document, finalize, getCurrentVersion, getCurrentVersion, getCurrentVersion, getDeleter, getVersion, indexExists, indexExists, indexExists, isCurrent, isLocked, isLocked, isOptimized, lastModified, lastModified, lastModified, main, open, open, open, setDeleter, setNorm, setNorm, undeleteAll, unlock

Methods inherited from class java.lang.Object

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

Constructor Detail

ParallelReader

public ParallelReader()
               throws IOException

Construct a ParallelReader.

Throws:

IOException

Method Detail

add

public void add(IndexReader reader)
         throws IOException

Add an IndexReader.

Throws:

IOException

add

public void add(IndexReader reader,
                boolean ignoreStoredFields)
         throws IOException

Add an IndexReader whose stored fields will not be returned. This can accellerate search when stored fields are only needed from a subset of the IndexReaders.

Throws:

IllegalArgumentException - if not all indexes contain the same number of documents

IllegalArgumentException - if not all indexes have the same value of IndexReader.maxDoc()

IOException

numDocs

public int numDocs()

Description copied from class: IndexReader

Returns the number of documents in this index.

Specified by:

numDocs in class IndexReader

maxDoc

public int maxDoc()

Description copied from class: IndexReader

Returns one greater than the largest possible document number. This may be used to, e.g., determine how big to allocate an array which will have an element for every document number in an index.

Specified by:

maxDoc in class IndexReader

hasDeletions

public boolean hasDeletions()

Description copied from class: IndexReader

Returns true if any documents have been deleted

Specified by:

hasDeletions in class IndexReader

isDeleted

public boolean isDeleted(int n)

Description copied from class: IndexReader

Returns true if document n has been deleted

Specified by:

isDeleted in class IndexReader

doDelete

protected void doDelete(int n)
                 throws IOException

Description copied from class: IndexReader

Implements deletion of the document numbered docNum. Applications should call IndexReader.deleteDocument(int) or IndexReader.deleteDocuments(Term).

Specified by:

doDelete in class IndexReader

Throws:

IOException

doUndeleteAll

protected void doUndeleteAll()
                      throws IOException

Description copied from class: IndexReader

Implements actual undeleteAll() in subclass.

Specified by:

doUndeleteAll in class IndexReader

Throws:

IOException

document

public Document document(int n,
                         FieldSelector fieldSelector)
                  throws IOException

Description copied from class: IndexReader

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 this 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:

document in class IndexReader

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:

IOException - If there is a problem reading this document

See Also:

Fieldable, FieldSelector, SetBasedFieldSelector, LoadFirstFieldSelector

getTermFreqVectors

public TermFreqVector[] getTermFreqVectors(int n)
                                    throws IOException

Description copied from class: IndexReader

Return an array of term frequency vectors for the specified document. The array contains a vector for each vectorized field in the document. Each vector contains terms and frequencies for all terms in a given vectorized field. If no such fields existed, the method returns null. The term vectors that are returned my either be of type TermFreqVector or of type TermPositionsVector if positions or offsets have been stored.

Specified by:

getTermFreqVectors in class IndexReader

Parameters:

n - document for which term frequency vectors are returned

Returns:

array of term frequency vectors. May be null if no term vectors have been stored for the specified document.

Throws:

IOException - if index cannot be accessed

See Also:

Field.TermVector

getTermFreqVector

public TermFreqVector getTermFreqVector(int n,
                                        String field)
                                 throws IOException

Description copied from class: IndexReader

Return a term frequency vector for the specified document and field. The returned vector contains terms and frequencies for the terms in the specified field of this document, if the field had the storeTermVector flag set. If termvectors had been stored with positions or offsets, a TermPositionsVector is returned.

Specified by:

getTermFreqVector in class IndexReader

Parameters:

n - document for which the term frequency vector is returned

field - field for which the term frequency vector is returned.

Returns:

term frequency vector May be null if field does not exist in the specified document or term vector was not stored.

Throws:

IOException - if index cannot be accessed

See Also:

Field.TermVector

hasNorms

public boolean hasNorms(String field)
                 throws IOException

Description copied from class: IndexReader

Returns true if there are norms stored for this field.

Overrides:

hasNorms in class IndexReader

Throws:

IOException

norms

public byte[] norms(String field)
             throws IOException

Description copied from class: IndexReader

Returns the byte-encoded normalization factor for the named field of every document. This is used by the search code to score documents.

Specified by:

norms in class IndexReader

Throws:

IOException

See Also:

AbstractField.setBoost(float)

norms

public void norms(String field,
                  byte[] result,
                  int offset)
           throws IOException

Description copied from class: IndexReader

Reads the byte-encoded normalization factor for the named field of every document. This is used by the search code to score documents.

Specified by:

norms in class IndexReader

Throws:

IOException

See Also:

AbstractField.setBoost(float)

doSetNorm

protected void doSetNorm(int n,
                         String field,
                         byte value)
                  throws IOException

Description copied from class: IndexReader

Implements setNorm in subclass.

Specified by:

doSetNorm in class IndexReader

Throws:

IOException

terms

public TermEnum terms()
               throws IOException

Description copied from class: IndexReader

Returns an enumeration of all the terms in the index. The enumeration is ordered by Term.compareTo(). Each term is greater than all that precede it in the enumeration.

Specified by:

terms in class IndexReader

Throws:

IOException

terms

public TermEnum terms(Term term)
               throws IOException

Description copied from class: IndexReader

Returns an enumeration of all terms after a given term. The enumeration is ordered by Term.compareTo(). Each term is greater than all that precede it in the enumeration.

Specified by:

terms in class IndexReader

Throws:

IOException

docFreq

public int docFreq(Term term)
            throws IOException

Description copied from class: IndexReader

Returns the number of documents containing the term t.

Specified by:

docFreq in class IndexReader

Throws:

IOException

termDocs

public TermDocs termDocs(Term term)
                  throws IOException

Description copied from class: IndexReader

Returns an enumeration of all the documents which contain term. For each document, the document number, the frequency of the term in that document is also provided, for use in search scoring. Thus, this method implements the mapping:

Term => <docNum, freq>^*

The enumeration is ordered by document number. Each document number is greater than all that precede it in the enumeration.

Overrides:

termDocs in class IndexReader

Throws:

IOException

termDocs

public TermDocs termDocs()
                  throws IOException

Description copied from class: IndexReader

Returns an unpositioned TermDocs enumerator.

Specified by:

termDocs in class IndexReader

Throws:

IOException

termPositions

public TermPositions termPositions(Term term)
                            throws IOException

Description copied from class: IndexReader

Returns an enumeration of all the documents which contain term. For each document, in addition to the document number and frequency of the term in that document, a list of all of the ordinal positions of the term in the document is available. Thus, this method implements the mapping:

Term => <docNum, freq, <pos₁, pos₂, ... pos_freq-1> >^*

This positional information faciliates phrase and proximity searching.

The enumeration is ordered by document number. Each document number is greater than all that precede it in the enumeration.

Overrides:

termPositions in class IndexReader

Throws:

IOException

termPositions

public TermPositions termPositions()
                            throws IOException

Description copied from class: IndexReader

Returns an unpositioned TermPositions enumerator.

Specified by:

termPositions in class IndexReader

Throws:

IOException

doCommit

protected void doCommit()
                 throws IOException

Description copied from class: IndexReader

Implements commit.

Specified by:

doCommit in class IndexReader

Throws:

IOException

doClose

protected void doClose()
                throws IOException

Description copied from class: IndexReader

Implements close.

Specified by:

doClose in class IndexReader

Throws:

IOException

getFieldNames

public Collection getFieldNames(IndexReader.FieldOption fieldNames)

Description copied from class: IndexReader

Get a list of unique field names that exist in this index and have the specified field option information.

Specified by:

getFieldNames in class IndexReader

Parameters:

fieldNames - specifies which field option should be available for the returned fields

Returns:

Collection of Strings indicating the names of the fields.

See Also:

IndexReader.FieldOption