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 Clownfish::Obj.