org.apache.lucene.index

Class 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: <!-- ======================================================== --> <!-- = Java Sourcecode to HTML automatically converted code = --> <!-- = Java2Html Converter V4.1 2004 by Markus Gebhard markus@jave.de = --> <!-- = Further information: http://www.java2html.de = -->

    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();
<!-- = END of automatically generated HTML code = --> <!-- ======================================================== -->

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(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.
IndexModifier(Directory directory, 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()

Field Details

analyzer

protected Analyzer analyzer

directory

protected Directory directory

indexReader

protected IndexReader indexReader

indexWriter

protected IndexWriter indexWriter

infoStream

protected PrintStream infoStream

maxBufferedDocs

protected int maxBufferedDocs

maxFieldLength

protected int maxFieldLength

mergeFactor

protected int mergeFactor

open

protected boolean open

useCompoundFile

protected boolean useCompoundFile

Constructor Details

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

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

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

Method Details

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.

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.

assureOpen

protected void assureOpen()
Throw an IllegalStateException if the index is closed.

close

public void close()
            throws IOException
Close this index, writing all pending changes to disk.

createIndexReader

protected void createIndexReader()
            throws IOException
Close the IndexWriter and open an IndexReader.

createIndexWriter

protected void createIndexWriter()
            throws IOException
Close the IndexReader and open an IndexWriter.

deleteDocument

public void deleteDocument(int docNum)
            throws IOException
Deletes the document numbered docNum.

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

docCount

public int docCount()
Returns the number of documents currently in this index.

flush

public void flush()
            throws IOException
Make sure all changes are written to disk.

getInfoStream

public PrintStream getInfoStream()
            throws IOException

getMaxBufferedDocs

public int getMaxBufferedDocs()
            throws IOException

getMaxFieldLength

public int getMaxFieldLength()
            throws IOException

getMergeFactor

public int getMergeFactor()
            throws IOException

getUseCompoundFile

public boolean getUseCompoundFile()
            throws IOException

init

protected void init(Directory directory,
                    Analyzer analyzer,
                    boolean create)
            throws IOException
Initialize an IndexWriter.

optimize

public void optimize()
            throws IOException
Merges all segments together into a single segment, optimizing an index for search.

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);


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.


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.


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.


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.

toString

public String toString()

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