org.apache.lucene.index
Class IndexModifier

java.lang.Object
  org.apache.lucene.index.IndexModifier

public class IndexModifier
extends Object

[Note that as of 2.1, all but one of the methods in this class are available via IndexWriter. The one method that is not available is deleteDocument(int).]

A class to modify an index, i.e. to delete and add documents. This class hides IndexReader and IndexWriter so that you do not need to care about implementation details such as that adding documents is done via IndexWriter and deletion is done via IndexReader.

Note that you cannot create more than one IndexModifier object on the same directory at the same time.

Example usage:

Analyzer analyzer = new StandardAnalyzer();
// create an index in /tmp/index, overwriting an existing one:
IndexModifier indexModifier = new IndexModifier("/tmp/index", analyzer, true);
Document doc = new Document();
doc.add(new Field("id", "1", Field.Store.YES, Field.Index.UN_TOKENIZED));
doc.add(new Field("body", "a simple test", Field.Store.YES, Field.Index.TOKENIZED));
indexModifier.addDocument(doc);
int deleted = indexModifier.delete(new Term("id", "1"));
System.out.println("Deleted " + deleted + " document");
indexModifier.flush();
System.out.println(indexModifier.docCount() + " docs in index");
indexModifier.close();

Not all methods of IndexReader and IndexWriter are offered by this class. If you need access to additional methods, either use those classes directly or implement your own class that extends IndexModifier.

Although an instance of this class can be used from more than one thread, you will not get the best performance. You might want to use IndexReader and IndexWriter directly for that (but you will need to care about synchronization yourself then).

While you can freely mix calls to add() and delete() using this class, you should batch you calls for best performance. For example, if you want to update 20 documents, you should first delete all those documents, then add all the new documents.

Author:

Daniel Naber

Field Summary

protected Analyzer	analyzer
protected Directory	directory
protected IndexReader	indexReader
protected IndexWriter	indexWriter
protected PrintStream	infoStream
protected int	maxBufferedDocs
protected int	maxFieldLength
protected int	mergeFactor
protected boolean	open
protected boolean	useCompoundFile

Constructor Summary

IndexModifier(Directory directory, Analyzer analyzer, boolean create)
Open an index with write access.

IndexModifier(File file, Analyzer analyzer, boolean create)
Open an index with write access.

IndexModifier(String dirName, Analyzer analyzer, boolean create)
Open an index with write access.

Method Summary

void	addDocument(Document doc) Adds a document to this index.
void	addDocument(Document doc, Analyzer docAnalyzer) Adds a document to this index, using the provided analyzer instead of the one specific in the constructor.
protected void	assureOpen() Throw an IllegalStateException if the index is closed.
void	close() Close this index, writing all pending changes to disk.
protected void	createIndexReader() Close the IndexWriter and open an IndexReader.
protected void	createIndexWriter() Close the IndexReader and open an IndexWriter.
void	deleteDocument(int docNum) Deletes the document numbered docNum.
int	deleteDocuments(Term term) Deletes all documents containing term.
int	docCount() Returns the number of documents currently in this index.
void	flush() Make sure all changes are written to disk.
PrintStream	getInfoStream()
int	getMaxBufferedDocs()
int	getMaxFieldLength()
int	getMergeFactor()
boolean	getUseCompoundFile()
protected void	init(Directory directory, Analyzer analyzer, boolean create) Initialize an IndexWriter.
void	optimize() Merges all segments together into a single segment, optimizing an index for search.
void	setInfoStream(PrintStream infoStream) If non-null, information about merges and a message when getMaxFieldLength() is reached will be printed to this.
void	setMaxBufferedDocs(int maxBufferedDocs) Determines the minimal number of documents required before the buffered in-memory documents are merging and a new Segment is created.
void	setMaxFieldLength(int maxFieldLength) The maximum number of terms that will be indexed for a single field in a document.
void	setMergeFactor(int mergeFactor) Determines how often segment indices are merged by addDocument().
void	setUseCompoundFile(boolean useCompoundFile) Setting to turn on usage of a compound file.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

indexWriter

protected IndexWriter indexWriter

indexReader

protected IndexReader indexReader

directory

protected Directory directory

analyzer

protected Analyzer analyzer

open

protected boolean open

infoStream

protected PrintStream infoStream

useCompoundFile

protected boolean useCompoundFile

maxBufferedDocs

protected int maxBufferedDocs

maxFieldLength

protected int maxFieldLength

mergeFactor

protected int mergeFactor

Constructor Detail

IndexModifier

public IndexModifier(Directory directory,
                     Analyzer analyzer,
                     boolean create)
              throws IOException

Open an index with write access.

Parameters:

directory - the index directory

analyzer - the analyzer to use for adding new documents

create - true to create the index or overwrite the existing one; false to append to the existing index

Throws:

IOException

IndexModifier

public IndexModifier(String dirName,
                     Analyzer analyzer,
                     boolean create)
              throws IOException

Open an index with write access.

Parameters:

dirName - the index directory

analyzer - the analyzer to use for adding new documents

create - true to create the index or overwrite the existing one; false to append to the existing index

Throws:

IOException

IndexModifier

public IndexModifier(File file,
                     Analyzer analyzer,
                     boolean create)
              throws IOException

Open an index with write access.

Parameters:

file - the index directory

analyzer - the analyzer to use for adding new documents

create - true to create the index or overwrite the existing one; false to append to the existing index

Throws:

IOException

Method Detail

init

protected void init(Directory directory,
                    Analyzer analyzer,
                    boolean create)
             throws IOException

Initialize an IndexWriter.

Throws:

IOException

assureOpen

protected void assureOpen()

Throw an IllegalStateException if the index is closed.

Throws:

IllegalStateException

createIndexWriter

protected void createIndexWriter()
                          throws IOException

Close the IndexReader and open an IndexWriter.

Throws:

IOException

createIndexReader

protected void createIndexReader()
                          throws IOException

Close the IndexWriter and open an IndexReader.

Throws:

IOException

flush

public void flush()
           throws IOException

Make sure all changes are written to disk.

Throws:

IOException

addDocument

public void addDocument(Document doc,
                        Analyzer docAnalyzer)
                 throws IOException

Adds a document to this index, using the provided analyzer instead of the one specific in the constructor. If the document contains more than setMaxFieldLength(int) terms for a given field, the remainder are discarded.

Throws:

IllegalStateException - if the index is closed

IOException

See Also:

IndexWriter.addDocument(Document, Analyzer)

addDocument

public void addDocument(Document doc)
                 throws IOException

Adds a document to this index. If the document contains more than setMaxFieldLength(int) terms for a given field, the remainder are discarded.

Throws:

IllegalStateException - if the index is closed

IOException

See Also:

IndexWriter.addDocument(Document)

deleteDocuments

public int deleteDocuments(Term term)
                    throws IOException

Deletes all documents containing term. This is useful if one uses a document field to hold a unique ID string for the document. Then to delete such a document, one merely constructs a term with the appropriate field and the unique ID string as its text and passes it to this method. Returns the number of documents deleted.

Returns:

the number of documents deleted

Throws:

IllegalStateException - if the index is closed

IOException

See Also:

IndexReader.deleteDocuments(Term)

deleteDocument

public void deleteDocument(int docNum)
                    throws IOException

Deletes the document numbered docNum.

Throws:

IllegalStateException - if the index is closed

IOException

See Also:

IndexReader.deleteDocument(int)

docCount

public int docCount()

Returns the number of documents currently in this index.

Throws:

IllegalStateException - if the index is closed

See Also:

IndexWriter.docCount(), IndexReader.numDocs()

optimize

public void optimize()
              throws IOException

Merges all segments together into a single segment, optimizing an index for search.

Throws:

IllegalStateException - if the index is closed

IOException

See Also:

IndexWriter.optimize()

setInfoStream

public void setInfoStream(PrintStream infoStream)

If non-null, information about merges and a message when getMaxFieldLength() is reached will be printed to this.

Example: index.setInfoStream(System.err);

Throws:

IllegalStateException - if the index is closed

See Also:

IndexWriter.setInfoStream(PrintStream)

getInfoStream

public PrintStream getInfoStream()
                          throws IOException

Throws:

IOException

See Also:

setInfoStream(PrintStream)

setUseCompoundFile

public void setUseCompoundFile(boolean useCompoundFile)

Setting to turn on usage of a compound file. When on, multiple files for each segment are merged into a single file once the segment creation is finished. This is done regardless of what directory is in use.

Throws:

IllegalStateException - if the index is closed

See Also:

IndexWriter.setUseCompoundFile(boolean)

getUseCompoundFile

public boolean getUseCompoundFile()
                           throws IOException

Throws:

IOException

See Also:

setUseCompoundFile(boolean)

setMaxFieldLength

public void setMaxFieldLength(int maxFieldLength)

The maximum number of terms that will be indexed for a single field in a document. This limits the amount of memory required for indexing, so that collections with very large files will not crash the indexing process by running out of memory.

Note that this effectively truncates large documents, excluding from the index terms that occur further in the document. If you know your source documents are large, be sure to set this value high enough to accomodate the expected size. If you set it to Integer.MAX_VALUE, then the only limit is your memory, but you should anticipate an OutOfMemoryError.

By default, no more than 10,000 terms will be indexed for a field.

Throws:

IllegalStateException - if the index is closed

See Also:

IndexWriter.setMaxFieldLength(int)

getMaxFieldLength

public int getMaxFieldLength()
                      throws IOException

Throws:

IOException

See Also:

setMaxFieldLength(int)

setMaxBufferedDocs

public void setMaxBufferedDocs(int maxBufferedDocs)

Determines the minimal number of documents required before the buffered in-memory documents are merging and a new Segment is created. Since Documents are merged in a RAMDirectory, large value gives faster indexing. At the same time, mergeFactor limits the number of files open in a FSDirectory.

The default value is 10.

Throws:

IllegalStateException - if the index is closed

IllegalArgumentException - if maxBufferedDocs is smaller than 2

See Also:

IndexWriter.setMaxBufferedDocs(int)

getMaxBufferedDocs

public int getMaxBufferedDocs()
                       throws IOException

Throws:

IOException

See Also:

setMaxBufferedDocs(int)

setMergeFactor

public void setMergeFactor(int mergeFactor)

Determines how often segment indices are merged by addDocument(). With smaller values, less RAM is used while indexing, and searches on unoptimized indices are faster, but indexing speed is slower. With larger values, more RAM is used during indexing, and while searches on unoptimized indices are slower, indexing is faster. Thus larger values (> 10) are best for batch index creation, and smaller values (< 10) for indices that are interactively maintained.

This must never be less than 2. The default value is 10.

Throws:

IllegalStateException - if the index is closed

See Also:

IndexWriter.setMergeFactor(int)

getMergeFactor

public int getMergeFactor()
                   throws IOException

Throws:

IOException

See Also:

setMergeFactor(int)

close

public void close()
           throws IOException

Close this index, writing all pending changes to disk.

Throws:

IllegalStateException - if the index has been closed before already

IOException

toString

public String toString()

Overrides:

toString in class Object