DO $$

BEGIN
  ALTER TABLE {SCHEMA_NAME}.postjobs ADD COLUMN last_worker_session_id UUID REFERENCES {SCHEMA_NAME}.worker_sessions ON DELETE CASCADE;
  UPDATE {SCHEMA_NAME}.postjobs SET last_worker_session_id={SCHEMA_NAME}._null_uuid();
  ALTER TABLE {SCHEMA_NAME}.postjobs ALTER COLUMN last_worker_session_id SET NOT NULL;
EXCEPTION
  WHEN duplicate_column THEN RAISE DEBUG 'column {SCHEMA_NAME}.postjobs.last_worker_session_id already exists';
END;

$$;

DO $$

BEGIN
  ALTER TABLE {SCHEMA_NAME}.postjobs DROP COLUMN workflow_status;
EXCEPTION
  WHEN undefined_column THEN RAISE DEBUG 'column {SCHEMA_NAME}.postjobs.workflow_status already dropped';
END;

$$;