From mst irc://irc.perl.org#dbix-class, 2016-12-27.
my $source = $schema->source('UserData');
my $new_source = $source->new(%$source, name => "user_data_${user_id}");
$schema->register_source('UserData_'.$user_id => $new_source);
my $rs = $schema->resultset('UserData_'.$user_id);
my $request_schema = $global_schema->clone;
$request_schema->source('UserData')->name("user_data_${user_id}");
# just use $request_schema and let it go away at the end of the request