NAME¶

Lucy::Index::Segment - Warehouse for information about one segment of an inverted index.

SYNOPSIS¶

    # Index-time.
    package MyDataWriter;
    use base qw( Lucy::Index::DataWriter );
    sub finish {
        my $self     = shift;
        my $segment  = $self->get_segment;
        my $metadata = $self->SUPER::metadata();
        $metadata->{foo} = $self->get_foo;
        $segment->store_metadata(
            key       => 'my_component',
            metadata  => $metadata
        );
    }
    # Search-time.
    package MyDataReader;
    use base qw( Lucy::Index::DataReader );
    sub new {
        my $self     = shift->SUPER::new(@_);
        my $segment  = $self->get_segment;
        my $metadata = $segment->fetch_metadata('my_component');
        if ($metadata) {
            $self->set_foo( $metadata->{foo} );
            ...
        }
        return $self;
    }

DESCRIPTION¶

Apache Lucy's indexes are made up of individual "segments", each of which is is an independent inverted index. On the file system, each segment is a directory within the main index directory whose name starts with "seg_": "seg_2", "seg_5a", etc.

Each Segment object keeps track of information about an index segment: its fields, document count, and so on. The Segment object itself writes one file, "segmeta.json"; besides storing info needed by Segment itself, the "segmeta" file serves as a central repository for metadata generated by other index components -- relieving them of the burden of storing metadata themselves.

METHODS¶

INHERITANCE¶

Lucy::Index::Segment isa Lucy::Object::Obj.