--up
    ALTER TABLE conductor_request_tags ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE config_vals ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE config_vals ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE device_tags ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE device_tags ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE embedded_strings ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE embedded_strings ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE faq_answers ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE faq_answers ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE faq_questions ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE faq_questions ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE preset_tags ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE preset_tags ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE sample_tags ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE sample_tags ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE shared_tracks_plays ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE shared_tracks_plays ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE signup_surveys ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE signup_surveys ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE tracks_for_sharing ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE tracks_for_sharing ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE user_identities ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE user_identities ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE users ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE users ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();
   
    ALTER TABLE voice_conversion_model_corpus ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();

    ALTER TABLE waiting_list_signups ADD COLUMN "created_at" timestamp NOT NULL DEFAULT NOW();
    ALTER TABLE waiting_list_signups ADD COLUMN "updated_at" timestamp NOT NULL DEFAULT NOW();

     
--down
    ALTER TABLE conductor_request_tags DROP COLUMN "created_at";

    ALTER TABLE config_vals DROP COLUMN "created_at";
    ALTER TABLE config_vals DROP COLUMN "updated_at";

    ALTER TABLE device_tags DROP COLUMN "created_at";
    ALTER TABLE device_tags DROP COLUMN "updated_at";

    ALTER TABLE embedded_strings DROP COLUMN "created_at";
    ALTER TABLE embedded_strings DROP COLUMN "updated_at";

    ALTER TABLE faq_answers DROP COLUMN "created_at";
    ALTER TABLE faq_answers DROP COLUMN "updated_at";

    ALTER TABLE faq_questions DROP COLUMN "created_at";
    ALTER TABLE faq_questions DROP COLUMN "updated_at";

    ALTER TABLE preset_tags DROP COLUMN "created_at";
    ALTER TABLE preset_tags DROP COLUMN "updated_at";

    ALTER TABLE sample_tags DROP COLUMN "created_at";
    ALTER TABLE sample_tags DROP COLUMN "updated_at";

    ALTER TABLE shared_tracks_plays DROP COLUMN "created_at";
    ALTER TABLE shared_tracks_plays DROP COLUMN "updated_at";

    ALTER TABLE signup_surveys DROP COLUMN "created_at";
    ALTER TABLE signup_surveys DROP COLUMN "updated_at";

    ALTER TABLE tracks_for_sharing DROP COLUMN "created_at";
    ALTER TABLE tracks_for_sharing DROP COLUMN "updated_at";

    ALTER TABLE user_identities DROP COLUMN "created_at";
    ALTER TABLE user_identities DROP COLUMN "updated_at";

    ALTER TABLE users DROP COLUMN "created_at";
    ALTER TABLE users DROP COLUMN "updated_at";

    ALTER TABLE voice_conversion_model_corpus DROP COLUMN "created_at";

    ALTER TABLE waiting_list_signups DROP COLUMN "created_at";
    ALTER TABLE waiting_list_signups DROP COLUMN "updated_at";
