DBIx::Class::OptimisticLocking - Optimistic locking support for DBIx::Class Optimistic locking is an alternative to using exclusive locks when you have the possibility of concurrent, conflicting updates in your database. The basic principle is you allow any and all clients to issue updates and rather than preemptively synchronizing all data modifications (which is what happens with exclusive locks) you are "optimistic" that updates won’t interfere with one another and the updates will only fail when they do in fact interfere with one another. Consider the following scenario (in timeline order, not in the same block of code): my $order = $schema->resultset('Orders')->find(1); # some other different, concurrent process loads the same object my $other_order = $schema->resultset('Orders')->find(1); $order->status('fraud review'); $other_order->status('processed'); $order->update; # this succeeds $other_order->update; # this fails when using optimistic locking Without optimistic locking (or exclusive locking), the example order would have two sequential updates issued with the second essentially erasing the results of the first. With optimistic locking, the second update (on $other_order) would fail. This optimistic locking is typically done by adding additional restrictions to the "WHERE" clause of the "UPDATE" statement. These additional restrictions ensure the data is still in the expected state before applying the update. This DBIx::Class::OptimisticLocking component provides a few different strategies for providing this functionality. INSTALLATION To install this module, run the following commands: perl Makefile.PL make make test make install SUPPORT AND DOCUMENTATION After installing, you can find documentation for this module with the perldoc command. perldoc DBIx::Class::OptimisticLocking You can also look for information at: RT, CPAN's request tracker http://rt.cpan.org/NoAuth/Bugs.html?Dist=DBIx-Class-OptimisticLocking AnnoCPAN, Annotated CPAN documentation http://annocpan.org/dist/DBIx-Class-OptimisticLocking CPAN Ratings http://cpanratings.perl.org/d/DBIx-Class-OptimisticLocking Search CPAN http://search.cpan.org/dist/DBIx-Class-OptimisticLocking/ COPYRIGHT AND LICENCE Copyright (C) 2008 Brian Phillips This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.