NAME

Class::DBI::Replication - Class::DBI for replicated database

SYNOPSIS

  package Film;
  use base qw(Class::DBI::Replication);
    
  Film->set_master('dbi:mysql:host=master', $user, $pw);
  Film->set_slaves(
      [ 'dbi:mysql:host=slave1', $user, $pw ],
      [ 'dbi:mysql:host=slave2', $user, $pw ],
  );

DESCRIPTION

Classs::DBI::Replication extends Class::DBI's persistence for replicated databases.

The idea is very simple. SELECT from slaves, INSERT/UPDATE/DELETE to master.

From http://www.mysql.com/doc/R/e/Replication_FAQ.html,

  Q: What should I do to prepare my client code to use
  performance-enhancing replication?

  A: If the part of your code that is responsible for database access
  has been properly abstracted/modularized, converting it to run with
  the replicated setup should be very smooth and easy - just change
  the implementation of your database access to read from some slave
  or the master, and to always write to the master.

With Class::DBI::Replication, it can be done easily!

METHODS

set_master

  Film->set_master($datasource, $user, $password, \%attr);

This spcifies your master database. INSERT/UPDATE/DELETE are done only to this database. Some SELECT queries also done to master for concurrency problem.

If you don't want master to be distinct from slaves in SELECT queries, put master in slaves, too.

set_slaves

  Film->set_slaves(
       [ 'dbi:mysql:host=slave1', $user, $password, \%attr ],
       [ 'dbi:mysql:host=slave2', $user, $password, \%attr ],
  );

This specifies your slave databases. SELECT are done to these databases randomly. If you don't specify slaves, all queries are gone to master, as always.

TODO

More docs
More testing
retrieve() adter create() problem. Currently, SELECT calls inside Class::DBI are done to master database.
Concurrency problems
Customizable slave picking algorithm like Round-Robin

AUTHOR

Tatsuhiko Miyagawa <miyagawa@bulknews.net>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

CPAN RT