Data::ObjectDriver::Driver::SimplePartition(3pm)

NAME
Data::ObjectDriver::Driver::SimplePartition - basic partitioned object driver

SYNOPSIS
    package ParentObject;
    use base qw( Data::ObjectDriver::BaseObject );

    __PACKAGE__->install_properties({
        columns     => [ 'parent_id', 'partition_id', ... ],
        ...
        driver      => Data::ObjectDriver::Driver::DBI->new( @$GLOBAL_DB_INFO ),
        primary_key => 'parent_id',
    });

    __PACKAGE__->has_partitions(
        number     => scalar @PARTITIONS,
        get_driver => \&get_driver_by_partition,
    );

    package SomeObject;
    use base qw( Data::ObjectDriver::BaseObject );

    __PACKAGE__->install_properties({
        ...
        driver               => Data::ObjectDriver::Driver::SimplePartition->new(
                                    using => 'ParentObject'
                                ),
        primary_key          => ['parent_id', 'object_id'],
    });

DESCRIPTION
Data::ObjectDriver::Driver::SimplePartition is a basic driver for objects partitioned into separate databases. See Data::ObjectDriver::Driver::Partition for more about partitioning databases.

SimplePartition helps you partition objects into databases based on their association with one record of a parent class. If your classes don't meet the requirements imposed by SimplePartition, you can still write your own partitioning driver. See Data::ObjectDriver::Driver::Partition.

SUGGESTED PRACTICES
Often this is used for user partitioning, where the parent class is your user account class; all records of other classes that are "owned" by that user are partitioned into the same database. This allows you to scale horizontally with the number of users, at the cost of complicating querying multiple users' data together.

SimplePartition will load the related instance of the parent class every time it needs to find the partition for a related object. Consider using a minimal mapping class for the parent, keeping as much data as possible in other related classes. For example, if "User" were your parent class, you might keep only the user ID and other data used to find users (such as login name and email address) in "User", keeping further profile data in another "UserProfile" class.

As all the partitioned classes related to a given parent class will share the same "partition_get_driver" logic to turn a partition ID into a driver, you might put the "partition_get_driver" function in the parent class, or use a custom subclass of SimplePartition that contains and automatically specifies the "partition_get_driver" function.

USAGE

  Data::ObjectDriver::Driver::SimplePartition->new(%params)
Creates a new basic partitioning driver for a particular class. The required members of %params are:

•   "using"

    The name of the parent class on which the driven class is partitioned.

    Using a class as a parent partitioned class requires these properties to be defined:

    •   "columns"

        The parent class must have a "partition_id" column containing a partition identifier. This identifier is passed to the "partition_get_driver" function to identify a driver to return.

    •   "primary_key"

        The parent class's primary key must be a simple single-column key, and that column must be the same as the referencing column in the partitioned classes.

    •   "partition_get_driver"

        The "partition_get_driver" property must be a function that returns an object driver, given a partition ID and any extra parameters given to the "SimplePartition" constructor.

        This property can also be defined as "get_driver" in a call to "Class->has_partitions()". See Data::ObjectDriver::BaseObject.

You can also include any further optional parameters you like. They will be passed to the partitioned class's "partition_get_driver" function as given.

A SimplePartition driver will require these properties to be defined for partitioned classes:

•   "primary_key"

    Your primary key should be a complex primary key (arrayref) with the simple key of the parent object for the first field.

DIAGNOSTICS

•   "using is required."

    The "using" parameter to the SimplePartition constructor is required to create the partitioned class's "get_driver" function. Perhaps you omitted it, or your subclass of SimplePartition did not properly specify it to its parent's constructor.

•   "Bogus classname."

    The parent class name you specified in your "using" parameter does not appear to be a valid class name. If you are automatically generating parent class names, check that your method of converting strings to class names is correct.

•   "Failed to load parent class: error"

    The parent class you specified in your "using" parameter could not be loaded, for the given reason. Perhaps you didn't include its location in your library path.

•   "Partitioning driver not defined for partitioned class"

    The partitioned class named in the error is configured to use the SimplePartition driver but does not have a "partition_get_driver" set. Check that you intended to use SimplePartition with that class or, if you're automatically specifying the "partition_get_driver" function, that your technique is working correctly.

•   "Cannot extract column from terms search terms or primary key"

    The SimplePartition driver could not determine from the given search terms or object key what the ID of the related parent record was. Check that your columns in the partitioned and parent classes share the same name, and that your application includes the parent ID in all search() calls for the partitioned class and instances of partitioned objects before attempting to save them.

    Optionally you can enable a basic support of search across multiple partition by passing the 'multi_partition' arg (true value) to the search query.

•   "Member of class with ID parent ID not found"

    The parent record associated with the partitioned object could not be loaded. Perhaps your application deleted the parent record without removing its associated partitioned objects first.

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

SEE ALSO
Data::ObjectDriver::Driver::Partition

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.