David Golden > Metabase > Metabase::Index

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Module Version: 1.001   Source   Latest Release: Metabase-1.003

NAME ^

Metabase::Index - Interface for Metabase indexing

VERSION ^

version 1.001

SYNOPSIS ^

  package Metabase::Index::Bar;
  use Metabase::Fact;
  use Moose;
  with 'Metabase::Index';

  # define Moose attributes

  sub add {
    my ( $self, $fact ) = @_;
    # index a fact
  }

  sub search {
    my ( $self, %spec ) = @_;
    # conduct search
    return \@matches;
  }

  # ... implement other required methods ... *

DESCRIPTION ^

This module defines a Moose::Role for indexing and searching facts. Implementations for any particular backend indexer must provide all of the required methods described below.

METHODS ^

The following methods are provided by the Metabase::Index role.

clone_metadata

  my $metadata = $index->clone_metadata( $fact )

Assembles all three metadata types ('core', 'resource' and 'content') into a single-level hash by joining the type and the metadata name with a period. E.g. the guid. field from the core metadata becomes core.guid.

exists

  if ( $index->exists( $guid ) ) { do_stuff() }

This method that calls search() on the given GUID and returns a boolean value.

search DEPRECATED

  for $guid ( @{ $index->search( %query ) } ) {
    # do stuff
  }

Returns an arrayref of GUIDs satisfying the query parameters. The query must be given in the form described in Metabase::Query.

This method is deprecated in favor of query and is included for backwards compatibility. It calls query and accumulates all results before returning.

METHODS REQUIRED ^

The following methods must be implemented by consumers of the Metabase::Index role.

Errors should throw exceptions rather than return false values.

add

  $index->add( $fact );

Adds the given fact to the Metabase Index;

query

  my $result = $index->search( %query );
  while ( ! $result->is_done ) {
    for $guid ( $result->items ) {
      # do stuff
    }
  }

Returns a Data::Stream::Bulk iterator. Calling the iterator will return lists of GUIDs satisfying the query parameters. The query must be given in the form described in Metabase::Query. Valid fields for search are the keys from core, content, or resource metadata. E.g.

  core.guid
  core.type
  core.resource
  resource.somefield
  content.somefield

See Data::Stream::Bulk for more on the iterator API.

count

  my $count = $index->count( %query );

Takes query parameters and returns a count of facts satisfying the parameters. The query must be given in the form described in Metabase::Query, though -order and -limit clauses should not be included.

There is no guarantee that this query will take any less time than calling query and counting all the results, though back end implementations are encouraged to optimize if possible. In the worst case, all results could be retrieved and then discarded.

delete

  $index->delete( $guid );

Removes the fact with matching GUID from the index.

initialize

  sub initialize {
    my ($self, @fact_classes) = @_;
    # prepare backend to store data (e.g. create database, etc.)
    return;
  }

Allows a backend to prepare to store various classes.

Metabase::Query methods

As Metabase::Index consumes the Metabase::Query role, all the required methods from that role must be implemented as well.

AUTHORS ^

COPYRIGHT AND LICENSE ^

This software is Copyright (c) 2012 by David Golden.

This is free software, licensed under:

  The Apache License, Version 2.0, January 2004
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