1Data::ObjectDriver::DriUvseerr::CPoanrttriitbiuotne(d3D)Paetral::DOobcjuemcetnDtraitvieorn::Driver::Partition(3)
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NAME

6       Data::ObjectDriver::Driver::Partition - base class for partitioned
7       object drivers
8

SYNOPSIS

10           package SomeObject;
11
12           __PACKAGE__->install_properties({
13               ...
14               primary_key => 'id',
15               driver      => Data::ObjectDriver::Driver::Partition->new(get_driver => \&find_partition),
16           });
17
18           # Say we have a list of 5 arrayrefs of the DBI driver information.
19           my @DBI_INFO;
20
21           sub find_partition {
22               my ($part_key, $args) = @_;
23
24               my $id;
25
26               if (ref $terms && ref $terms eq 'HASH') {
27                   # This is a search($terms, $args) call.
28                   my $terms = $part_key;
29                   $id = $terms->{id}
30                       or croak "Can't determine partition from a search() with no id field";
31               }
32               else {
33                   # This is a lookup($id) or some method invoked on an object where we know the ID.
34                   my $id = $part_key;
35               }
36
37               # "ID modulo N" is not a good partitioning strategy, but serves as an example.
38               my $partition = $id % 5;
39               return Data::ObjectDriver::Driver::DBI->new( @{ $DBI_INFO[$partition] } );
40           }
41

DESCRIPTION

43       Data::ObjectDriver::Driver::Partition provides the basic structure for
44       partitioning objects into different databases. Using partitions, you
45       can horizontally scale your application by using different database
46       servers to hold sets of data.
47
48       To partition data, you need a certain criteria to determine which
49       partition data goes in. Partition drivers use a "get_driver" function
50       to find the database driver for the correct partition, given either the
51       arguments to a "search()" or the object's primary key for a "lookup()",
52       "update()", etc where the key is known.
53

SUGGESTED PRACTICES

55       While you can use any stable, predictable method of selecting the
56       partition for an object, the most flexible way is to keep an
57       unpartitioned table that maps object keys to their partitions. You can
58       then look up the appropriate record in your get_driver method to find
59       the partition.
60
61       For many applications, you can partition several classes of data based
62       on the ID of the user account that "owns" them. In this case, you would
63       include the user ID as the first part of a complex primary key.
64
65       Because multiple objects can use the same partitioning scheme, often
66       Data::ObjectDriver::Driver::Partition is subclassed to define the
67       "get_driver" function once and automatically specify it to the
68       Data::ObjectDriver::Driver::Partition constructor.
69
70       Note these practices are codified into the
71       Data::ObjectDriver::Driver::SimplePartition class.
72

USAGE

74   "Data::ObjectDriver::Driver::Partition->new(%params)"
75       Creates a new partitioning driver. The required members of %params are:
76
77       ·   "get_driver"
78
79           A reference to a function to be used to retrieve for a given object
80           or set of search terms. Your function is invoked as either:
81
82           ·   "get_driver(\%terms, \%args)"
83
84               Return a driver based on the given "search()" parameters.
85
86           ·   "get_driver($id)"
87
88               Return a driver based on the given object ID. Note that $id may
89               be an arrayref, if the class was defined with a complex primary
90               key.
91
92       ·   "pk_generator"
93
94           A reference to a function that, given a data object, generates a
95           primary key for it. This is the same "pk_generator" given to
96           "Data::ObjectDriver"'s constructor.
97
98   "$driver->search($class, $terms, $args)"
99   "$driver->lookup($class, $id)"
100   "$driver->lookup_multi($class, @ids)"
101   "$driver->exists($obj)"
102   "$driver->insert($obj)"
103   "$driver->update($obj)"
104   "$driver->remove($obj)"
105   "$driver->fetch_data($what)"
106       Performs the named action, by passing these methods through to the
107       appropriate database driver as determined by $driver's "get_driver"
108       function.
109

DIAGNOSTICS

111       No errors are created by Data::ObjectDriver::Driver::Partition itself.
112       Errors may come from a specific partitioning subclass or the driver for
113       a particular database.
114

BUGS AND LIMITATIONS

116       There are no known bugs in this module.
117

SEE ALSO

119       Data::ObjectDriver::Driver::SimplePartition
120

LICENSE

122       Data::ObjectDriver is free software; you may redistribute it and/or
123       modify it under the same terms as Perl itself.
124

126       Except where otherwise noted, Data::ObjectDriver is Copyright 2005-2006
127       Six Apart, cpan@sixapart.com. All rights reserved.
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131perl v5.12.0                      2010-D0a3t-a2:2:ObjectDriver::Driver::Partition(3)
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