NAME

       Lucy::Docs::DocIDs - Characteristics of Apache Lucy document ids.

DESCRIPTION

   Document ids are signed 32-bit integers
       Document ids in Apache Lucy 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 ) {
               ...
           }

   Document ids are ephemeral
       The document ids used by Lucy 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, Lucy 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.