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Lucene-0.01
River stage one • 1 direct dependent • 1 total dependent
++
/ Lucene

NAME

Lucene -- API to the C++ port of the Lucene search engine

SYNOPSIS

Initialize/Empty Lucene index

  my $analyzer = new Lucene::Analysis::Standard::StandardAnalyzer();
  my $store = Lucene::Store::FSDirectory->getDirectory("/home/lucene", 1);

  my $tmp_writer = new Lucene::Index::IndexWriter($store, $analyzer, 1);
  $tmp_writer->close;
  undef $tmp_writer;

Choose your Analyzer (string tokenizer):

  # lowercases text and splits it at non-letter characters 
  my $analyzer = Lucene::Analysis::SimpleAnalyzer();
  # same as before and removes stop words
  my $analyzer = Lucene::Analysis::StopAnalyzer();
  # splits text at whitespace characters
  my $analyzer = Lucene::Analysis::WhitespaceAnalyzer();
  # lowercases text, tokenized it based on a grammer that 
  # leaves named authorities intact (e-mails, company names,
  # web hostnames, IP addresses, etc) and removed stop words
  my $analyzer = Lucene::Analysis::Standard::StandardAnalyzer();

Choose your Store (storage engine):

  # in-memory storage
  my $store = new Lucene::Store::RAMDirectory();
  # disk-based storage
  my $store = Lucene::Store::FSDirectory->getDirectory("/home/lucene", 0);

Open and configure an IndexWriter:

  my $writer = new Lucene::Index::IndexWriter($store, $analyzer, 0);
  # optional settings for power users
  $writer->setMergeFactor(100);
  $writer->setUseCompoundFile(0);
  $writer->setMaxFieldLength(255);
  $writer->setMinMergeDocs(10);
  $writer->setMaxMergeDocs(100);

Create Documents and add Fields:

  my $doc = new Lucene::Document;
  # field gets analyzed, indexed and stored
  $doc->add(Lucene::Document::Field->Text("content", $content));
  # field gets indexed and stored
  $doc->add(Lucene::Document::Field->Keyword("isbn", $isbn));
  # field gets just stored
  $doc->add(Lucene::Document::Field->UnIndexed("sales_rank", $sales_rank));
  # field gets analyzed and indexed 
  $doc->add(Lucene::Document::Field->UnStored("categories", $categories));

Add Documents to an IndexWriter:

  $writer->addDocument($doc);

Optimize your index and close the IndexWriter:

  $writer->optimize();
  $writer->close();
  undef $writer;

Delete Documents:

  my $reader = Lucene::Index::IndexReader->open($store);
  my $term = new Lucene::Index::Term("isbn", $isbn);
  $reader->deleteDocuments($term);
  $reader->close();
  undef $reader;

Query index:

  # initalize searcher and parser
  my $analyzer = Lucene::Analysis::SimpleAnalyzer();
  my $store = Lucene::Store::FSDirectory->getDirectory("/home/lucene", 0);
  my $searcher = new Lucene::Search::IndexSearcher($store);
  my $parser = new Lucene::QueryParser("default_field", $analyzer);

  # build a query on the default field
  my $query = $parser->parse("perl");

  # build a query on another field
  my $query = $parser->parse("title:cookbook");

  # query index and get results
  my $hits = $searcher->search($query);

  # get number of results
  my $num_hits = $hits->length();

  # get fields and ranking score for each hit
  for (my $i = 0; $i < $num_hits; $i++) {
    my $doc = $hits->doc($i);
    my $score = $hits->score($i);
    my $title = $doc->get("title");
    my $isbn = $doc->get("isbn");
  }

  # free memory and close searcher
  undef $hits;
  undef $query;
  undef $parser;
  undef $analyzer;
  $searcher->close();
  undef $fsdir;
  undef $searcher;
}

Close your Store:

  $store->close;
  undef $store;

DESCRIPTION

Like it or not Apache Lucene has become the de-facto standard for open-source high-performance search. It has a large user-base, is well documented and has plenty of committers. Unfortunately Apache Lucene is entirely written in Java and therefore of relatively little use for perl programmers. Fortunately in the recent years a group of C++ programmers led by Ben van Klinken decided to port Java Lucene to C++.

The purpose of the module is to export the C++ Lucene API to perl and at the same time be as close as possible to the original Java API. This has the combined advantage of providing perl programmers with a well-documented API and giving them access to a C++ search engine library that is supposedly faster than the original.

CHARACTER SUPPORT

Currently only ISO 8859-1 (Latin-1) characters are supported. Obviously this included all ASCII characters.

INDEX COMPATIBLITY

For the moment indices produced by this module are not compatible with those from Apache Lucene. The reason for this is that this module uses 1-byte character encoding as opposed to 2-byte (widechar) encoding with Apache Lucene.

INSTALLATION

This module requires the clucene library to be installed. The best way to get it is to go to the following page

    http://sourceforge.net/projects/clucene/

and download the latest STABLE clucene-core version. Currently it is clucene-core-0.9.15. Make sure you compile it in ASCII mode and install it in your standard library path.

On a Linux platform this goes as follows:

    wget http://kent.dl.sourceforge.net/sourceforge/clucene/clucene-core-0.9.15.tar.gz
    cd clucene-core-0.9.15
    ./autogen.sh
    ./configure --disable-debug --prefix=/usr --exec-prefix=/usr --enable-ascii
    make
    make check
    (as root) make install

To install the perl module itself, run the following commands:

    perl Makefile.PL
    make
    make test
    (as root) make install

AUTHOR

Thomas Busch <tbusch at cpan dot org>

COPYRIGHT AND LICENSE

Copyright (c) 2006 Thomas Busch

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO

Plucene - a pure-Perl implementation of Lucene

Kinosearch - a search engine library inspired by Lucene

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.