NAME

       Lucy::Index::DataWriter - Write data to an index.

SYNOPSIS

           # Abstract base class.

DESCRIPTION

       DataWriter is an abstract base class for writing index data, generally in segment-sized
       chunks. Each component of an index -- e.g. stored fields, lexicon, postings, deletions --
       is represented by a DataWriter/DataReader pair.

       Components may be specified per index by subclassing Architecture.

CONSTRUCTORS

   new( [labeled params] )
           my $writer = MyDataWriter->new(
               snapshot   => $snapshot,      # required
               segment    => $segment,       # required
               polyreader => $polyreader,    # required
           );

       •   snapshot - The Snapshot that will be committed at the end of the indexing session.

       •   segment - The Segment in progress.

       •   polyreader - A PolyReader representing all existing data in the index.  (If the index
           is brand new, the PolyReader will have no sub-readers).

ABSTRACT METHODS

   add_inverted_doc( [labeled params] )
       Process a document, previously inverted by "inverter".

       •   inverter - An Inverter wrapping an inverted document.

       •   doc_id - Internal number assigned to this document within the segment.

   add_segment( [labeled params] )
       Add content from an existing segment into the one currently being written.

       •   reader - The SegReader containing content to add.

       •   doc_map - An array of integers mapping old document ids to new.  Deleted documents are
           mapped to 0, indicating that they should be skipped.

   finish()
       Complete the segment: close all streams, store metadata, etc.

   format()
       Every writer must specify a file format revision number, which should increment each time
       the format changes. Responsibility for revision checking is left to the companion
       DataReader.

METHODS

   delete_segment(reader)
       Remove a segment's data.  The default implementation is a no-op, as all files within the
       segment directory will be automatically deleted.  Subclasses which manage their own files
       outside of the segment system should override this method and use it as a trigger for
       cleaning up obsolete data.

       •   reader - The SegReader containing content to merge, which must represent a segment
           which is part of the the current snapshot.

   merge_segment( [labeled params] )
       Move content from an existing segment into the one currently being written.

       The default implementation calls add_segment() then delete_segment().

       •   reader - The SegReader containing content to merge, which must represent a segment
           which is part of the the current snapshot.

       •   doc_map - An array of integers mapping old document ids to new.  Deleted documents are
           mapped to 0, indicating that they should be skipped.

   metadata()
       Arbitrary metadata to be serialized and stored by the Segment.  The default implementation
       supplies a Hash with a single key-value pair for "format".

   get_snapshot()
       Accessor for "snapshot" member var.

   get_segment()
       Accessor for "segment" member var.

   get_polyreader()
       Accessor for "polyreader" member var.

   get_schema()
       Accessor for "schema" member var.

   get_folder()
       Accessor for "folder" member var.

INHERITANCE

       Lucy::Index::DataWriter isa Lucy::Object::Obj.