Improved job phase triggers

-- Trigger function that automatically updates start time and end time of jobs at phase update.

-- This could be performed by business logic of each application that handles jobs but relying directly on the database ensures a better uniformity.

CREATE OR REPLACE FUNCTION job_phase_inserted() RETURNS TRIGGER 

AS 

$func$

BEGIN

    IF new.phase = 'EXECUTING' THEN

        new.start_time := NOW();

    ELSIF new.phase = 'COMPLETED' OR new.phase = 'ERROR' THEN

        new.start_time := NOW();

        new.end_time := NOW();

    END IF;

    RETURN new;

END;

$func$ LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION job_phase_updated() RETURNS TRIGGER 

AS 

$func$

BEGIN

    IF new.phase != old.phase THEN

        IF new.phase = 'EXECUTING' THEN

            new.start_time := NOW();

        ELSIF new.phase = 'COMPLETED' OR new.phase = 'ERROR' OR new.phase = 'ABORTED' THEN

            new.end_time := NOW();

        END IF;

    END IF;

    RETURN new;

END;

$func$ LANGUAGE plpgsql;

CREATE TRIGGER job_update

    BEFORE UPDATE OF phase ON job

    FOR EACH ROW

    EXECUTE PROCEDURE job_phase_updated();

CREATE TRIGGER job_insert

    BEFORE INSERT ON job

    FOR EACH ROW

    EXECUTE PROCEDURE job_phase_inserted();

CREATE TRIGGER job_update

    BEFORE UPDATE OF phase ON job

    FOR EACH ROW

    EXECUTE PROCEDURE job_phase_updated();