Xapian(3pm)

NAME
Search::Xapian - Perl XS frontend to the Xapian C++ search library.

SYNOPSIS
  use Search::Xapian;

  my $db = Search::Xapian::Database->new( '[DATABASE DIR]' );
  my $enq = $db->enquire( '[QUERY TERM]' );

  printf "Running query '%s'\n", $enq->get_query()->get_description();

  my @matches = $enq->matches(0, 10);

  print scalar(@matches) . " results found\n";

  foreach my $match ( @matches ) {
    my $doc = $match->get_document();
    printf "ID %d %d%% [ %s ]\n", $match->get_docid(), $match->get_percent(), $doc->get_data();
  }

DESCRIPTION
This module wraps most methods of most Xapian classes. The missing classes and methods should be added in the future. It also provides a simplified, more 'perlish' interface to some common operations, as demonstrated above.

There are some gaps in the POD documentation for wrapped classes, but you can read the Xapian C++ API documentation at <https://xapian.org/docs/apidoc/html/annotated.html> for details of these. Alternatively, take a look at the code in the examples and tests.

If you want to use Search::Xapian and the threads module together, make sure you're using Search::Xapian >= 1.0.4.0 and Perl >= 5.8.7. As of 1.0.4.0, Search::Xapian uses CLONE_SKIP to make sure that the perl wrapper objects aren't copied to new threads - without this the underlying C++ objects can get destroyed more than once.

If you encounter problems, or have any comments, suggestions, patches, etc please email the Xapian-discuss mailing list (details of which can be found at <https://xapian.org/lists>).

  EXPORT
None by default.

:db

DB_OPEN
    Open a database, fail if database doesn't exist.

DB_CREATE
    Create a new database, fail if database exists.

DB_CREATE_OR_OPEN
    Open an existing database, without destroying data, or create a new database if one doesn't already exist.

DB_CREATE_OR_OVERWRITE
    Overwrite database if it exists.

:ops

OP_AND
    Match if both subqueries are satisfied.

OP_OR
    Match if either subquery is satisfied.

OP_AND_NOT
    Match if left but not right subquery is satisfied.

OP_XOR
    Match if left or right, but not both queries are satisfied.

OP_AND_MAYBE
    Match if left is satisfied, but use weights from both.

OP_FILTER
    Like OP_AND, but only weight using the left query.

OP_NEAR
    Match if the words are near each other. The window should be specified, as a parameter to "Search::Xapian::Query::Query", but it defaults to the number of terms in the list.

OP_PHRASE
    Match as a phrase (All words in order).

OP_ELITE_SET
    Select an elite set from the subqueries, and perform a query with these combined as an OR query.

OP_VALUE_RANGE
    Filter by a range test on a document value.

:qpflags

FLAG_DEFAULT
    This gives the QueryParser default flag settings, allowing you to easily add flags to the default ones.

FLAG_BOOLEAN
    Support AND, OR, etc and bracketed subexpressions.

FLAG_LOVEHATE
    Support + and -.

FLAG_PHRASE
    Support quoted phrases.

FLAG_BOOLEAN_ANY_CASE
    Support AND, OR, etc even if they aren't in ALLCAPS.

FLAG_WILDCARD
    Support right truncation (e.g. Xap*).

FLAG_PURE_NOT
    Allow queries such as 'NOT apples'.

    These require the use of a list of all documents in the database which is potentially expensive, so this feature isn't enabled by default.

FLAG_PARTIAL
    Enable partial matching.

    Partial matching causes the parser to treat the query as a "partially entered" search. This will automatically treat the final word as a wildcarded match, unless it is followed by whitespace, to produce more stable results from interactive searches.

FLAG_SPELLING_CORRECTION
FLAG_SYNONYM
FLAG_AUTO_SYNONYMS
FLAG_AUTO_MULTIWORD_SYNONYMS

:qpstem

STEM_ALL
    Stem all terms.

STEM_NONE
    Don't stem any terms.

STEM_SOME
    Stem some terms, in a manner compatible with Omega (capitalised words and those in phrases aren't stemmed).

:enq_order

ENQ_ASCENDING
    docids sort in ascending order (default)

ENQ_DESCENDING
    docids sort in descending order

ENQ_DONT_CARE
    docids sort in whatever order is most efficient for the backend

:standard
Standard is db + ops + qpflags + qpstem

Version functions

major_version
    Returns the major version of the Xapian C++ library being used. E.g. for Xapian 1.0.9 this would return 1.

minor_version
    Returns the minor version of the Xapian C++ library being used. E.g. for Xapian 1.0.9 this would return 0.

revision
    Returns the revision of the Xapian C++ library being used. E.g. for Xapian 1.0.9 this would return 9. In a stable release series, Xapian libraries with the same minor and major versions are usually ABI compatible, so this often won't match the third component of $Search::Xapian::VERSION (which is the version of the Search::Xapian XS wrappers).

Numeric encoding functions

sortable_serialise NUMBER
    Convert a floating point number to a string, preserving sort order.

    This method converts a floating point number to a string, suitable for using as a value for numeric range restriction, or for use as a sort key.

    The conversion is platform independent.

    The conversion attempts to ensure that, for any pair of values supplied to the conversion algorithm, the result of comparing the original values (with a numeric comparison operator) will be the same as the result of comparing the resulting values (with a string comparison operator). On platforms which represent doubles with the precisions specified by IEEE_754, this will be the case: if the representation of doubles is more precise, it is possible that two very close doubles will be mapped to the same string, so will compare equal.

    Note also that both zero and -zero will be converted to the same representation: since these compare equal, this satisfies the comparison constraint, but it's worth knowing this if you wish to use the encoding in some situation where this distinction matters.

    Handling of NaN isn't (currently) guaranteed to be sensible.

sortable_unserialise SERIALISED_NUMBER
    Convert a string encoded using sortable_serialise back to a floating point number.

    This expects the input to be a string produced by sortable_serialise(). If the input is not such a string, the value returned is undefined (but no error will be thrown).

    The result of the conversion will be exactly the value which was supplied to sortable_serialise() when making the string on platforms which represent doubles with the precisions specified by IEEE_754, but may be a different (nearby) value on other platforms.

TODO

Error Handling
    Error handling for all methods liable to generate them.

Documentation
    Add POD documentation for all classes, where possible just adapted from Xapian docs.

Unwrapped classes
    The following Xapian classes are not yet wrapped: ErrorHandler, standard ExpandDecider subclasses (user-defined ones works), user-defined weight classes.

Unwrapped methods
    The following methods are not yet wrapped: Enquire::get_eset(...) with more than two arguments, Query ctor optional "parameter" parameter, Remote::open(...), static Stem::get_available_languages().

    We wrap MSet::swap() and MSet::operator[](), but not ESet::swap(), ESet::operator[](). Is swap actually useful? Should we instead tie MSet and ESet to allow them to just be used as lists?

CREDITS
Thanks to Tye McQueen <tye@metronet.com> for explaining the finer points of how best to write XS frontends to C++ libraries, James Aylett <james@tartarus.org> for clarifying the less obvious aspects of the Xapian API, Tim Brody for patches wrapping ::QueryParser and ::Stopper and especially Olly Betts <olly@survex.com> for contributing advice, bugfixes, and wrapper code for the more obscure classes.

AUTHOR
Alex Bowley <kilinrax@cpan.org>

Please report any bugs/suggestions to <xapian-discuss@lists.xapian.org> or use the Xapian bug tracker <https://xapian.org/bugs>. Please do NOT use the CPAN bug tracker or mail any of the authors individually.

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

SEE ALSO
Search::Xapian::BM25Weight, Search::Xapian::BoolWeight, Search::Xapian::Database, Search::Xapian::Document, Search::Xapian::Enquire, Search::Xapian::MatchSpy, Search::Xapian::MultiValueSorter, Search::Xapian::PositionIterator, Search::Xapian::PostingIterator, Search::Xapian::QueryParser, Search::Xapian::Stem, Search::Xapian::TermGenerator, Search::Xapian::TermIterator, Search::Xapian::TradWeight, Search::Xapian::ValueIterator, Search::Xapian::Weight, Search::Xapian::WritableDatabase, and <https://xapian.org/>.