Data::ObjectDriver::Driver::Partition man page on Pidora

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Data::ObjectDriver::DrUser:ContributedData::ObjectDriver::Driver::Partition(3)

NAME
       Data::ObjectDriver::Driver::Partition - base class for partitioned
       object drivers

SYNOPSIS
	   package SomeObject;

	   __PACKAGE__->install_properties({
	       ...
	       primary_key => 'id',
	       driver	   => Data::ObjectDriver::Driver::Partition->new(get_driver => \&find_partition),
	   });

	   # Say we have a list of 5 arrayrefs of the DBI driver information.
	   my @DBI_INFO;

	   sub find_partition {
	       my ($part_key, $args) = @_;

	       my $id;

	       if (ref $terms && ref $terms eq 'HASH') {
		   # This is a search($terms, $args) call.
		   my $terms = $part_key;
		   $id = $terms->{id}
		       or croak "Can't determine partition from a search() with no id field";
	       }
	       else {
		   # This is a lookup($id) or some method invoked on an object where we know the ID.
		   my $id = $part_key;
	       }

	       # "ID modulo N" is not a good partitioning strategy, but serves as an example.
	       my $partition = $id % 5;
	       return Data::ObjectDriver::Driver::DBI->new( @{ $DBI_INFO[$partition] } );
	   }

DESCRIPTION
       Data::ObjectDriver::Driver::Partition provides the basic structure for
       partitioning objects into different databases. Using partitions, you
       can horizontally scale your application by using different database
       servers to hold sets of data.

       To partition data, you need a certain criteria to determine which
       partition data goes in. Partition drivers use a "get_driver" function
       to find the database driver for the correct partition, given either the
       arguments to a "search()" or the object's primary key for a "lookup()",
       "update()", etc where the key is known.

SUGGESTED PRACTICES
       While you can use any stable, predictable method of selecting the
       partition for an object, the most flexible way is to keep an
       unpartitioned table that maps object keys to their partitions. You can
       then look up the appropriate record in your get_driver method to find
       the partition.

       For many applications, you can partition several classes of data based
       on the ID of the user account that "owns" them. In this case, you would
       include the user ID as the first part of a complex primary key.

       Because multiple objects can use the same partitioning scheme, often
       Data::ObjectDriver::Driver::Partition is subclassed to define the
       "get_driver" function once and automatically specify it to the
       Data::ObjectDriver::Driver::Partition constructor.

       Note these practices are codified into the
       Data::ObjectDriver::Driver::SimplePartition class.

USAGE
   "Data::ObjectDriver::Driver::Partition->new(%params)"
       Creates a new partitioning driver. The required members of %params are:

       ·   "get_driver"

	   A reference to a function to be used to retrieve for a given object
	   or set of search terms. Your function is invoked as either:

	   ·   "get_driver(\%terms, \%args)"

	       Return a driver based on the given "search()" parameters.

	   ·   "get_driver($id)"

	       Return a driver based on the given object ID. Note that $id may
	       be an arrayref, if the class was defined with a complex primary
	       key.

       ·   "pk_generator"

	   A reference to a function that, given a data object, generates a
	   primary key for it. This is the same "pk_generator" given to
	   "Data::ObjectDriver"'s constructor.

   "$driver->search($class, $terms, $args)"
   "$driver->lookup($class, $id)"
   "$driver->lookup_multi($class, @ids)"
   "$driver->exists($obj)"
   "$driver->insert($obj)"
   "$driver->update($obj)"
   "$driver->remove($obj)"
   "$driver->fetch_data($what)"
       Performs the named action, by passing these methods through to the
       appropriate database driver as determined by $driver's "get_driver"
       function.

DIAGNOSTICS
       No errors are created by Data::ObjectDriver::Driver::Partition itself.
       Errors may come from a specific partitioning subclass or the driver for
       a particular database.

BUGS AND LIMITATIONS
       There are no known bugs in this module.

SEE ALSO
       Data::ObjectDriver::Driver::SimplePartition

LICENSE
       Data::ObjectDriver is free software; you may redistribute it and/or
       modify it under the same terms as Perl itself.

AUTHOR & COPYRIGHT
       Except where otherwise noted, Data::ObjectDriver is Copyright 2005-2006
       Six Apart, cpan@sixapart.com. All rights reserved.

perl v5.14.1			  2010Data::ObjectDriver::Driver::Partition(3)
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