Reference

Lucy::Index::Segment(3pm)

Warehouse for information about one segment of an inverted index.

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

add_field(field)

Register a new field and assign it a field number. If the field was already known, nothing happens.

•

field - Field name.

Returns: the field's field number, which is a positive integer.

store_metadata( [labeled params] )

Store arbitrary information in the segment's metadata Hash, to be serialized later. Throws an error if "key" is used twice.

•

key - String identifying an index component.

•

metadata - JSON-izable data structure.

fetch_metadata(key)

Fetch a value from the Segment's metadata hash.

field_num(field)

Given a field name, return its field number for this segment (which may differ from its number in other segments). Return 0 (an invalid field number) if the field name can't be found.

•

field - Field name.

field_name(field_num)

Given a field number, return the name of its field, or undef if the field name can't be found.

get_name()

Getter for the object's seg name.

get_number()

Getter for the segment number.

set_count(count)

Setter for the object's document count.

get_count()

Getter for the object's document count.

INHERITANCE

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

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