Do I need to manually create indexes for a DBIx::Class belongs_to relationship

Question

I'm using the DBIx::Class modules for an ORM approach to an application I have.

I'm having some problems with my relationships.

I have the following

package MySchema::Result::ClusterIP;
use strict;
use warnings;

use base qw/DBIx::Class::Core/;

our $VERSION = '1.0';

__PACKAGE__->load_components(qw/InflateColumn::Object::Enum Core/);
__PACKAGE__->table('cluster_ip');

__PACKAGE__->add_columns( # Columns here );

__PACKAGE__->set_primary_key('objkey');
__PACKAGE__->belongs_to( 'configuration' => 'MySchema::Result::Configuration', 'config_key');
__PACKAGE__->belongs_to( 'cluster' => 'MySchema::Result::Cluster',
                            { 'foreign.config_key' => 'self.config_key',
                              'foreign.id'         => 'self.cluster_id'
                            }
                        );

As well as

package MySchema::Result::Cluster;
use strict;
use warnings;

use base qw/DBIx::Class::Core/;

our $VERSION = '1.0';

__PACKAGE__->load_components(qw/InflateColumn::Object::Enum Core/);
__PACKAGE__->table('cluster');

__PACKAGE__->add_columns(  # Columns here );
__PACKAGE__->set_primary_key('objkey');
__PACKAGE__->belongs_to( 'configuration' => 'MySchema::Result::Configuration', 'config_key');
__PACKAGE__->has_many('cluster_ip'  => 'MySchema::Result::ClusterIP',
                            { 'foreign.config_key' => 'self.config_key',
                              'foreign.cluster_id' => 'self.id'
                            });

There are a couple of other modules, but I don't believe that they are relevant.

When I attempt to deploy this schema, I get the following error:

DBIx::Class::Schema::deploy(): DBI Exception: DBD::mysql::db do failed: Can't create table 'test.cluster_ip' (errno: 150) [
for Statement "CREATE TABLE `cluster_ip` (
  `objkey` smallint(5) unsigned NOT NULL auto_increment,
  `config_key` smallint(5) unsigned NOT NULL,
  `cluster_id` char(16) NOT NULL,
  INDEX `cluster_ip_idx_config_key_cluster_id` (`config_key`, `cluster_id`),
  INDEX `cluster_ip_idx_config_key` (`config_key`),
  PRIMARY KEY (`objkey`),
  CONSTRAINT `cluster_ip_fk_config_key_cluster_id` FOREIGN KEY (`config_key`, `cluster_id`) REFERENCES `cluster` (`config_key`, `id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `cluster_ip_fk_config_key` FOREIGN KEY (`config_key`) REFERENCES `configuration` (`config_key`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB"] at test_deploy.pl line 18

 (running "CREATE TABLE `cluster_ip` (
  `objkey` smallint(5) unsigned NOT NULL auto_increment,
  `config_key` smallint(5) unsigned NOT NULL,
  `cluster_id` char(16) NOT NULL,
  INDEX `cluster_ip_idx_config_key_cluster_id` (`config_key`, `cluster_id`),
  INDEX `cluster_ip_idx_config_key` (`config_key`),
  PRIMARY KEY (`objkey`),
  CONSTRAINT `cluster_ip_fk_config_key_cluster_id` FOREIGN KEY (`config_key`, `cluster_id`) REFERENC
ES `cluster` (`config_key`, `id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `cluster_ip_fk_config_key` FOREIGN KEY (`config_key`) REFERENCES `configuration` (`conf
ig_key`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB") at test_deploy.pl line 18

From what I can tell, MySQL is complaining about the FOREIGN KEY constraint, in particular, the REFERENCE to (config_key, id) in the cluster table. From my reading of the MySQL documentation, this seems like a reasonable complaint, especially in regards to the third bullet point on this doc page.

Here's my question. Am I missing something in the DBIx::Class module? I realize that I could explicitly create the necessary index to match up with this foreign key constraint, but that seems to be repetitive work. Is there something I should be doing to make this occur implicitly?

Answer 1

Not sure what is happening here as SQL::Translator::Producer::MySQL should insert SET foreign_key_checks=0 at the start of the deployed DDL so no foreign key errors should occur. I suspect something is broken even after the whole DDL is deployed. You can find out the exact nature of the foreign key error by connecting to the DB and running this statement:

SHOW INNODB STATUS;

Answer 2

I just fixed this same problem by adding the following into my result classes that were causing problems:

sub sqlt_deploy_hook {
   my ($self, $sqlt_table) = @_;
   $sqlt_table->add_index(name => 'idx_my_column', fields => ['my_column']);
}