Log row changes in PostgreSQL - Any advice/improvement is welcome ;-)

postgresql_changes_tracking.sql

/**
 * Creates a "logging" schema with an "history" table where are stored records in JSON format
 * 
 * Requires PostgreSQL >= 9.3 since data is stored in JSON format
 *
 * Credits: http://www.cybertec.at/2013/12/tracking-changes-in-postgresql/
 */

/* Create a schema dedicated to logs */
CREATE SCHEMA logging;

/* Create the table in which to store logs */
CREATE TABLE logging.history (
    id              serial,
    time            timestamptz DEFAULT CURRENT_TIMESTAMP,
    schema_name     text,
    table_name      text,
    user_name       text        DEFAULT current_user,
    operation       text,
    new_row         json,
    old_row         json
);

/* Create the function */
CREATE OR REPLACE FUNCTION logging.change_trigger() RETURNS trigger AS $$
    BEGIN
        IF    (TG_OP = 'INSERT') THEN
            INSERT INTO logging.history (table_name, schema_name, operation, new_row)
                VALUES (TG_RELNAME, TG_TABLE_SCHEMA, TG_OP, row_to_json(NEW));
            RETURN NEW;
        ELSIF (TG_OP = 'UPDATE') THEN
            INSERT INTO logging.history (table_name, schema_name, operation, new_row, old_row)
                VALUES (TG_RELNAME, TG_TABLE_SCHEMA, TG_OP, row_to_json(NEW), row_to_json(OLD));
            RETURN NEW;
        ELSIF (TG_OP = 'DELETE') THEN
            INSERT INTO logging.history (table_name, schema_name, operation, old_row)
                VALUES (TG_RELNAME, TG_TABLE_SCHEMA, TG_OP, row_to_json(OLD));
            RETURN OLD;
        END IF;
        RETURN NULL;
    END;
$$ LANGUAGE 'plpgsql' SECURITY DEFINER;

/* Create the triggers */
/* Single statement: change <schema_name> and <table_name> according to your needs */
/* 
DROP TRIGGER IF EXISTS table_change_trigger ON <schema_name>.<table_name>;
CREATE TRIGGER table_change_trigger 
    BEFORE INSERT OR UPDATE OR DELETE ON <schema_name>.<table_name>
    FOR EACH ROW EXECUTE PROCEDURE logging.change_trigger();
*/
/* Selects all tables in "public" schema and outputs the statements you need to execute for create the triggers */
SELECT 'DROP TRIGGER IF EXISTS table_change_trigger ON ' || schemaname || '.' || tablename || ';
    CREATE TRIGGER table_change_trigger 
    BEFORE INSERT OR UPDATE OR DELETE ON ' || schemaname || '.' || tablename || '
    FOR EACH ROW EXECUTE PROCEDURE logging.change_trigger();
' AS trigger_statements_to_execute
FROM pg_tables 
WHERE schemaname = 'public';

Thanks! Is it possible to use the logging table to revert the table back to a pervious state?