Data::ObjectDriver::DrUser:ContrData::ObjectDriver::Driver::SimplePartition(3)NAMEData::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'],
});
DESCRIPTIONData::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.
Optionaly you can enable a basic support of search accross 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.
perl v5.14.1Data::ObjectDriver::Driver::SimplePartition(3)
