=head1 NAME

KinoSearch::Docs::DocIDs - Characteristics of KinoSearch document ids.

=head1 DESCRIPTION

=head2 Document ids are signed 32-bit integers

Document ids in KinoSearch start at 1.  Because 0 is never a valid doc id, we
can use it as a sentinel value:

    while ( my $doc_id = $posting_list->next ) {
        ...
    }

=head2 Document ids are ephemeral

The document ids used by KinoSearch are associated with a single index
snapshot.  The moment an index is updated, the mapping of document ids to
documents is subject to change.

Since IndexReader objects represent a point-in-time view of an index, document
ids are guaranteed to remain static for the life of the reader.  However,
because they are not permanent, KinoSearch document ids cannot be used as
foreign keys to locate records in external data sources.  If you truly need a
primary key field, you must define it and populate it yourself.

Furthermore, the order of document ids does not tell you anything about the
sequence in which documents were added to the index.

=head1 COPYRIGHT

Copyright 2008-2009 Marvin Humphrey

=head1 LICENSE, DISCLAIMER, BUGS, etc.

See L<KinoSearch> version 0.30.

=cut