MultiReader (Lucene 2.9.4 API)

java.lang.Object
- org.apache.lucene.index.IndexReader
- - org.apache.lucene.index.MultiReader

All Implemented Interfaces:

java.lang.Cloneable
```
public class MultiReader
extends IndexReader
implements java.lang.Cloneable
```
An IndexReader which reads multiple indexes, appending their content.

Version:

$Id: MultiReader.java 950451 2010-06-02 09:33:57Z mikemccand $

Nested Class Summary
- Nested classes/interfaces inherited from class org.apache.lucene.index.IndexReader
  IndexReader.FieldOption

Field Summary

Fields
Modifier and Type Field and Description

protected IndexReader[] subReaders
- Fields inherited from class org.apache.lucene.index.IndexReader
  hasChanges

Fields
Modifier and Type	Field and Description
`protected IndexReader[]`	`subReaders`

Constructor Summary

Constructors
Constructor and Description
`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

All Methods Instance Methods Concrete Methods Deprecated Methods
Modifier and Type	Method and Description
`java.lang.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()` Deprecated.
`protected void`	`doCommit(java.util.Map 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, java.lang.String field, byte value)` Implements setNorm in subclass.
`protected void`	`doUndeleteAll()` Implements actual undeleteAll() in subclass.
`java.util.Collection`	`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, java.lang.String field)` Return a term frequency vector for the specified document and field.
`void`	`getTermFreqVector(int docNumber, java.lang.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(java.lang.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(java.lang.String field)` Returns the byte-encoded normalization factor for the named field of every document.
`void`	`norms(java.lang.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.
`IndexReader`	`reopen()` Tries to reopen the subreaders.
`TermDocs`	`termDocs()` Returns an unpositioned `TermDocs` enumerator.
`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, getCurrentVersion, getCurrentVersion, getCurrentVersion, getDeletesCacheKey, getDisableFakeNorms, getFieldCacheKey, getIndexCommit, getRefCount, getTermInfosIndexDivisor, getUniqueTermCount, incRef, indexExists, indexExists, indexExists, isLocked, isLocked, lastModified, lastModified, lastModified, listCommits, main, numDeletedDocs, open, open, open, open, open, open, open, open, open, open, open, open, open, open, reopen, reopen, setDisableFakeNorms, setNorm, setNorm, setTermInfosIndexDivisor, termDocs, termPositions, undeleteAll, unlock

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, 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
    
    Throws:
    
    java.io.IOException
  - 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
    
    Throws:
    
    java.io.IOException
- Method Detail
  - reopen
```
public IndexReader reopen()
                   throws CorruptIndexException,
                          java.io.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
    
    java.io.IOException - if there is a low-level IO error
  - clone
```
public java.lang.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,
                               java.io.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
    
    java.io.IOException
  - getTermFreqVectors
```
public TermFreqVector[] getTermFreqVectors(int n)
                                    throws java.io.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:
    
    java.io.IOException - if index cannot be accessed
    
    See Also:
    
    Field.TermVector
  - getTermFreqVector
```
public TermFreqVector getTermFreqVector(int n,
                                        java.lang.String field)
                                 throws java.io.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:
    
    java.io.IOException - if index cannot be accessed
    
    See Also:
    
    Field.TermVector
  - getTermFreqVector
```
public void getTermFreqVector(int docNumber,
                              java.lang.String field,
                              TermVectorMapper mapper)
                       throws java.io.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:
    
    java.io.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 java.io.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:
    
    java.io.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,
                         java.io.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 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:
    
    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,
                        java.io.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
    
    java.io.IOException
  - doUndeleteAll
```
protected void doUndeleteAll()
                      throws CorruptIndexException,
                             java.io.IOException
```
    Description copied from class: IndexReader
    
    Implements actual undeleteAll() in subclass.
    
    Specified by:
    
    doUndeleteAll in class IndexReader
    
    Throws:
    
    CorruptIndexException
    
    java.io.IOException
  - hasNorms
```
public boolean hasNorms(java.lang.String field)
                 throws java.io.IOException
```
    Description copied from class: IndexReader
    
    Returns true if there are norms stored for this field.
    
    Overrides:
    
    hasNorms in class IndexReader
    
    Throws:
    
    java.io.IOException
  - norms
```
public byte[] norms(java.lang.String field)
             throws java.io.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:
    
    java.io.IOException
    
    See Also:
    
    AbstractField.setBoost(float)
  - norms
```
public void norms(java.lang.String field,
                  byte[] result,
                  int offset)
           throws java.io.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:
    
    java.io.IOException
    
    See Also:
    
    AbstractField.setBoost(float)
  - doSetNorm
```
protected void doSetNorm(int n,
                         java.lang.String field,
                         byte value)
                  throws CorruptIndexException,
                         java.io.IOException
```
    Description copied from class: IndexReader
    
    Implements setNorm in subclass.
    
    Specified by:
    
    doSetNorm in class IndexReader
    
    Throws:
    
    CorruptIndexException
    
    java.io.IOException
  - terms
```
public TermEnum terms()
               throws java.io.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:
    
    java.io.IOException - if there is a low-level IO error
  - terms
```
public TermEnum terms(Term term)
               throws java.io.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:
    
    java.io.IOException - if there is a low-level IO error
  - docFreq
```
public int docFreq(Term t)
            throws java.io.IOException
```
    Description copied from class: IndexReader
    
    Returns the number of documents containing the term t.
    
    Specified by:
    
    docFreq in class IndexReader
    
    Throws:
    
    java.io.IOException - if there is a low-level IO error
  - termDocs
```
public TermDocs termDocs()
                  throws java.io.IOException
```
    Description copied from class: IndexReader
    
    Returns an unpositioned TermDocs enumerator.
    
    Specified by:
    
    termDocs in class IndexReader
    
    Throws:
    
    java.io.IOException - if there is a low-level IO error
  - termPositions
```
public TermPositions termPositions()
                            throws java.io.IOException
```
    Description copied from class: IndexReader
    
    Returns an unpositioned TermPositions enumerator.
    
    Specified by:
    
    termPositions in class IndexReader
    
    Throws:
    
    java.io.IOException - if there is a low-level IO error
  - doCommit
```
protected void doCommit()
                 throws java.io.IOException
```
    Deprecated.
    
    Description copied from class: IndexReader
    
    Implements commit.
    
    Specified by:
    
    doCommit in class IndexReader
    
    Throws:
    
    java.io.IOException
  - doCommit
```
protected void doCommit(java.util.Map commitUserData)
                 throws java.io.IOException
```
    Description copied from class: IndexReader
    
    Implements commit. NOTE: subclasses should override this. In 3.0 this will become an abstract method.
    
    Throws:
    
    java.io.IOException
  - doClose
```
protected void doClose()
                throws java.io.IOException
```
    Description copied from class: IndexReader
    
    Implements close.
    
    Specified by:
    
    doClose in class IndexReader
    
    Throws:
    
    java.io.IOException
  - getFieldNames
```
public java.util.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
  - isCurrent
```
public boolean isCurrent()
                  throws CorruptIndexException,
                         java.io.IOException
```
    Checks recursively if all subreaders are up to date.
    
    Overrides:
    
    isCurrent in class IndexReader
    
    Throws:
    
    CorruptIndexException - if the index is corrupt
    
    java.io.IOException - if there is a low-level IO error
  - getVersion
```
public long getVersion()
```
    Not implemented.
    
    Overrides:
    
    getVersion in class IndexReader
    
    Throws:
    
    java.lang.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(java.lang.String). Use the parent reader directly.
    
    Overrides:
    
    getSequentialSubReaders in class IndexReader

Class MultiReader

Nested Class Summary

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

Field Summary

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

Constructor Summary

Method Summary

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

Methods inherited from class java.lang.Object

Field Detail

subReaders

Constructor Detail

MultiReader

MultiReader

Method Detail

reopen

clone

doReopen

getTermFreqVectors

getTermFreqVector

getTermFreqVector

getTermFreqVector

isOptimized

numDocs

maxDoc

document

isDeleted

hasDeletions

doDelete

doUndeleteAll

hasNorms

norms

norms

doSetNorm

terms

terms

docFreq

termDocs

termPositions

doCommit

doCommit

doClose

getFieldNames

isCurrent

getVersion

getSequentialSubReaders