org.apache.lucene.index
Class MultiReader

java.lang.Object
  extended by org.apache.lucene.index.IndexReader
      extended by org.apache.lucene.index.MultiReader
All Implemented Interfaces:
Closeable, Cloneable

public class MultiReader
extends IndexReader
implements Cloneable

An IndexReader which reads multiple indexes, appending their content.


Nested Class Summary
 
Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader
IndexReader.FieldOption, IndexReader.ReaderFinishedListener
 
Field Summary
protected  IndexReader[] subReaders
           
 
Fields inherited from class org.apache.lucene.index.IndexReader
hasChanges, readerFinishedListeners
 
Constructor Summary
MultiReader(IndexReader... subReaders)
          Construct a MultiReader aggregating the named set of (sub)readers.
MultiReader(IndexReader[] subReaders, boolean closeSubReaders)
          Construct a MultiReader aggregating the named set of (sub)readers.
 
Method Summary
 void addReaderFinishedListener(IndexReader.ReaderFinishedListener listener)
          Expert: adds a IndexReader.ReaderFinishedListener.
 Object clone()
          Clones the subreaders.
 int docFreq(Term t)
          Returns the number of documents containing the term t.
protected  void doClose()
          Implements close.
protected  void doCommit(Map<String,String> commitUserData)
          Implements commit.
 Document document(int n, FieldSelector fieldSelector)
          Get the Document at the n th position.
protected  void doDelete(int n)
          Implements deletion of the document numbered docNum.
protected  IndexReader doReopen(boolean doClone)
          If clone is true then we clone each of the subreaders
protected  void doSetNorm(int n, String field, byte value)
          Implements setNorm in subclass.
protected  void doUndeleteAll()
          Implements actual undeleteAll() in subclass.
 Collection<String> getFieldNames(IndexReader.FieldOption fieldNames)
          Get a list of unique field names that exist in this index and have the specified field option information.
 IndexReader[] getSequentialSubReaders()
          Expert: returns the sequential sub readers that this reader is logically composed of.
 TermFreqVector getTermFreqVector(int n, String field)
          Return a term frequency vector for the specified document and field.
 void getTermFreqVector(int docNumber, String field, TermVectorMapper mapper)
          Load the Term Vector into a user-defined data structure instead of relying on the parallel arrays of the TermFreqVector.
 void getTermFreqVector(int docNumber, TermVectorMapper mapper)
          Map all the term vectors for all fields in a Document
 TermFreqVector[] getTermFreqVectors(int n)
          Return an array of term frequency vectors for the specified document.
 long getVersion()
          Not implemented.
 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 isCurrent()
          Checks recursively if all subreaders are up to date.
 boolean isDeleted(int n)
          Returns true if document n has been deleted
 boolean isOptimized()
          Checks is the index is optimized (if it has a single segment and no deletions).
 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.
 void removeReaderFinishedListener(IndexReader.ReaderFinishedListener listener)
          Expert: remove a previously added IndexReader.ReaderFinishedListener.
 IndexReader reopen()
          Tries to reopen the subreaders.
 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.
 TermEnum terms()
          Returns an enumeration of all the terms in the index.
 TermEnum terms(Term term)
          Returns an enumeration of all terms starting at a given term.
 
Methods inherited from class org.apache.lucene.index.IndexReader
acquireWriteLock, clone, close, commit, commit, decRef, deleteDocument, deleteDocuments, directory, document, ensureOpen, flush, flush, getCommitUserData, getCommitUserData, getCoreCacheKey, getCurrentVersion, getDeletesCacheKey, getIndexCommit, getRefCount, getTermInfosIndexDivisor, getUniqueTermCount, incRef, indexExists, lastModified, listCommits, main, notifyReaderFinishedListeners, numDeletedDocs, open, open, open, open, open, open, open, open, readerFinished, reopen, reopen, reopen, setNorm, setNorm, termPositions, toString, undeleteAll
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

subReaders

protected IndexReader[] subReaders
Constructor Detail

MultiReader

public MultiReader(IndexReader... subReaders)

Construct a MultiReader aggregating the named set of (sub)readers. Directory locking for delete, undeleteAll, and setNorm operations is left to the subreaders.

Note that all subreaders are closed if this Multireader is closed.

Parameters:
subReaders - set of (sub)readers

MultiReader

public MultiReader(IndexReader[] subReaders,
                   boolean closeSubReaders)

Construct a MultiReader aggregating the named set of (sub)readers. Directory locking for delete, undeleteAll, and setNorm operations is left to the subreaders.

Parameters:
closeSubReaders - indicates whether the subreaders should be closed when this MultiReader is closed
subReaders - set of (sub)readers
Method Detail

reopen

public IndexReader reopen()
                   throws CorruptIndexException,
                          IOException
Tries to reopen the subreaders.
If one or more subreaders could be re-opened (i. e. subReader.reopen() returned a new instance != subReader), then a new MultiReader instance is returned, otherwise this instance is returned.

A re-opened instance might share one or more subreaders with the old instance. Index modification operations result in undefined behavior when performed before the old instance is closed. (see IndexReader.reopen()).

If subreaders are shared, then the reference count of those readers is increased to ensure that the subreaders remain open until the last referring reader is closed.

Overrides:
reopen in class IndexReader
Throws:
CorruptIndexException - if the index is corrupt
IOException - if there is a low-level IO error

clone

public Object clone()
Clones the subreaders. (see IndexReader.clone()).

If subreaders are shared, then the reference count of those readers is increased to ensure that the subreaders remain open until the last referring reader is closed.

Overrides:
clone in class IndexReader

doReopen

protected IndexReader doReopen(boolean doClone)
                        throws CorruptIndexException,
                               IOException
If clone is true then we clone each of the subreaders

Parameters:
doClone -
Returns:
New IndexReader, or same one (this) if reopen/clone is not necessary
Throws:
CorruptIndexException
IOException

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 may either be of type TermFreqVector or of type TermPositionVector 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 TermPositionVector 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

getTermFreqVector

public void getTermFreqVector(int docNumber,
                              String field,
                              TermVectorMapper mapper)
                       throws IOException
Description copied from class: IndexReader
Load the Term Vector into a user-defined data structure instead of relying on the parallel arrays of the TermFreqVector.

Specified by:
getTermFreqVector in class IndexReader
Parameters:
docNumber - The number of the document to load the vector for
field - The name of the field to load
mapper - The TermVectorMapper to process the vector. Must not be null
Throws:
IOException - if term vectors cannot be accessed or if they do not exist on the field and doc. specified.

getTermFreqVector

public void getTermFreqVector(int docNumber,
                              TermVectorMapper mapper)
                       throws IOException
Description copied from class: IndexReader
Map all the term vectors for all fields in a Document

Specified by:
getTermFreqVector in class IndexReader
Parameters:
docNumber - The number of the document to load the vector for
mapper - The TermVectorMapper to process the vector. Must not be null
Throws:
IOException - if term vectors cannot be accessed or if they do not exist on the field and doc. specified.

isOptimized

public boolean isOptimized()
Description copied from class: IndexReader
Checks is the index is optimized (if it has a single segment and no deletions). Not implemented in the IndexReader base class.

Overrides:
isOptimized in class IndexReader
Returns:
true if the index is optimized; false otherwise

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

document

public Document document(int n,
                         FieldSelector fieldSelector)
                  throws CorruptIndexException,
                         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.

NOTE: for performance reasons, this method does not check if the requested document is deleted, and therefore asking for a deleted document may yield unspecified results. Usually this is not required, however you can call IndexReader.isDeleted(int) with the requested document ID to verify the document is not deleted.

Specified by:
document in class IndexReader
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:
Fieldable, FieldSelector, SetBasedFieldSelector, LoadFirstFieldSelector

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

hasDeletions

public boolean hasDeletions()
Description copied from class: IndexReader
Returns true if any documents have been deleted

Specified by:
hasDeletions in class IndexReader

doDelete

protected void doDelete(int n)
                 throws CorruptIndexException,
                        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:
CorruptIndexException
IOException

doUndeleteAll

protected void doUndeleteAll()
                      throws CorruptIndexException,
                             IOException
Description copied from class: IndexReader
Implements actual undeleteAll() in subclass.

Specified by:
doUndeleteAll in class IndexReader
Throws:
CorruptIndexException
IOException

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. Returns null if norms were not indexed for this field.

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 CorruptIndexException,
                         IOException
Description copied from class: IndexReader
Implements setNorm in subclass.

Specified by:
doSetNorm in class IndexReader
Throws:
CorruptIndexException
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. Note that after calling terms(), TermEnum.next() must be called on the resulting enumeration before calling other methods such as TermEnum.term().

Specified by:
terms in class IndexReader
Throws:
IOException - if there is a low-level IO error

terms

public TermEnum terms(Term term)
               throws IOException
Description copied from class: IndexReader
Returns an enumeration of all terms starting at a given term. If the given term does not exist, the enumeration is positioned at the first term greater than the supplied 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 - if there is a low-level IO error

docFreq

public int docFreq(Term t)
            throws IOException
Description copied from class: IndexReader
Returns the number of documents containing the term t.

Specified by:
docFreq in class IndexReader
Throws:
IOException - if there is a low-level IO error

termDocs

public TermDocs termDocs()
                  throws IOException
Description copied from class: IndexReader
Returns an unpositioned TermDocs enumerator.

Note: the TermDocs returned is unpositioned. Before using it, ensure that you first position it with TermDocs.seek(Term) or TermDocs.seek(TermEnum).

Specified by:
termDocs in class IndexReader
Throws:
IOException - if there is a low-level IO error

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. If term is null, then all non-deleted docs are returned with freq=1. Thus, this method implements the mapping:

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 - if there is a low-level IO error

termPositions

public TermPositions termPositions()
                            throws IOException
Description copied from class: IndexReader
Returns an unpositioned TermPositions enumerator.

Specified by:
termPositions in class IndexReader
Throws:
IOException - if there is a low-level IO error

doCommit

protected void doCommit(Map<String,String> commitUserData)
                 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<String> 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

isCurrent

public boolean isCurrent()
                  throws CorruptIndexException,
                         IOException
Checks recursively if all subreaders are up to date.

Overrides:
isCurrent in class IndexReader
Throws:
CorruptIndexException - if the index is corrupt
IOException - if there is a low-level IO error

getVersion

public long getVersion()
Not implemented.

Overrides:
getVersion in class IndexReader
Throws:
UnsupportedOperationException

getSequentialSubReaders

public IndexReader[] getSequentialSubReaders()
Description copied from class: IndexReader
Expert: returns the sequential sub readers that this reader is logically composed of. For example, IndexSearcher uses this API to drive searching by one sub reader at a time. If this reader is not composed of sequential child readers, it should return null. If this method returns an empty array, that means this reader is a null reader (for example a MultiReader that has no sub readers).

NOTE: You should not try using sub-readers returned by this method to make any changes (setNorm, deleteDocument, etc.). While this might succeed for one composite reader (like MultiReader), it will most likely lead to index corruption for other readers (like DirectoryReader obtained through IndexReader.open(org.apache.lucene.store.Directory). Use the parent reader directly.

Overrides:
getSequentialSubReaders in class IndexReader

addReaderFinishedListener

public void addReaderFinishedListener(IndexReader.ReaderFinishedListener listener)
Description copied from class: IndexReader
Expert: adds a IndexReader.ReaderFinishedListener. The provided listener is also added to any sub-readers, if this is a composite reader. Also, any reader reopened or cloned from this one will also copy the listeners at the time of reopen.

Overrides:
addReaderFinishedListener in class IndexReader

removeReaderFinishedListener

public void removeReaderFinishedListener(IndexReader.ReaderFinishedListener listener)
Description copied from class: IndexReader
Expert: remove a previously added IndexReader.ReaderFinishedListener.

Overrides:
removeReaderFinishedListener in class IndexReader


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