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 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 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.