NAME

Lucy::Index::IndexReader - Read from an inverted index.

SYNOPSIS

my $reader = Lucy::Index::IndexReader->open(
    index => '/path/to/index',
);
my $seg_readers = $reader->seg_readers;
for my $seg_reader (@$seg_readers) {
    my $seg_name = $seg_reader->get_segment->get_name;
    my $num_docs = $seg_reader->doc_max;
    print "Segment $seg_name ($num_docs documents):\n";
    my $doc_reader = $seg_reader->obtain("Lucy::Index::DocReader");
    for my $doc_id ( 1 .. $num_docs ) {
        my $doc = $doc_reader->fetch_doc($doc_id);
        print "  $doc_id: $doc->{title}\n";
    }
}

DESCRIPTION

IndexReader is the interface through which IndexSearcher objects access the content of an index.

IndexReader objects always represent a point-in-time view of an index as it existed at the moment the reader was created. If you want search results to reflect modifications to an index, you must create a new IndexReader after the update process completes.

IndexReaders are composites; most of the work is done by individual DataReader sub-components, which may be accessed via fetch() and obtain(). The most efficient and powerful access to index data happens at the segment level via SegReader’s sub-components.

CONSTRUCTORS

open

my $reader = Lucy::Index::IndexReader->open(
    index    => '/path/to/index', # required
    snapshot => $snapshot,
    manager  => $index_manager,
);

IndexReader is an abstract base class; open() returns the IndexReader subclass PolyReader, which channels the output of 0 or more SegReaders.

• index - Either a string filepath or a Folder.
• snapshot - A Snapshot. If not supplied, the most recent snapshot file will be used.
• manager - An IndexManager. Read-locking is off by default; supplying this argument turns it on.

ABSTRACT METHODS

doc_max

my $int = $index_reader->doc_max();

Return the maximum number of documents available to the reader, which is also the highest possible internal document id. Documents which have been marked as deleted but not yet purged from the index are included in this count.

doc_count

my $int = $index_reader->doc_count();

Return the number of documents available to the reader, subtracting any that are marked as deleted.

del_count

my $int = $index_reader->del_count();

Return the number of documents which have been marked as deleted but not yet purged from the index.

offsets

my $i32_array = $index_reader->offsets();

Return an array with one entry for each segment, corresponding to segment doc_id start offset.

seg_readers

my $arrayref = $index_reader->seg_readers();

Return an array of all the SegReaders represented within the IndexReader.

METHODS

obtain

my $data_reader = $index_reader->obtain($api);

Fetch a component, or throw an error if the component can’t be found.

• api - The name of the DataReader subclass that the desired component must implement.

fetch

my $data_reader = $index_reader->fetch($api);

Fetch a component, or return undef if the component can’t be found.

• api - The name of the DataReader subclass that the desired component must implement.

INHERITANCE

Lucy::Index::IndexReader isa Lucy::Index::DataReader isa Clownfish::Obj.