Diff.pm

  my $schema = shift;  # ISA DBIx::Class::Schema

  use SQL::Translator;
  use SQL::Translator::Diff;

  my $target_schema = SQL::Translator->new(
    parser => 'SQL::Translator::Parser::DBIx::Class',
    parser_args => {
      dbic_schema => $schema,
    },
  )->translate;

  my $source_schema =  SQL::Translator->new(
    parser => 'DBI',
    parser_args => { dsn => $ENV{DBI_DSN} }
  )->translate;

  my $diff = SQL::Translator::Diff->new({
    output_db     => 'PostgreSQL',
    source_schema => $source_schema,
    target_schema => $target_schema,
  })->compute_differences->produce_diff_sql;

When I run this I get output like

-- Convert schema '' to 'Liminal::Schema v1':;

BEGIN;

DROP INDEX person_pkey;

ALTER TABLE person ALTER COLUMN id TYPE serial;

ALTER TABLE person ALTER COLUMN username TYPE character varying(48);

ALTER TABLE person ALTER COLUMN email TYPE character varying(48);

ALTER TABLE person ALTER COLUMN password TYPE character varying(64);

ALTER TABLE person ADD PRIMARY KEY (id);

DROP TABLE marks CASCADE;

DROP TABLE students CASCADE;

DROP TABLE courses CASCADE;

DROP TABLE tests CASCADE;

DROP TABLE dbix_class_deploymenthandler_versions CASCADE;


COMMIT;