def create_schema(alembic_config_ini=None):
    """Create the database schema.

    :param alembic_config_ini: When provided, stamp with the current revision
    version.

    """
    Base.metadata.create_all()
    if alembic_config_ini:
        from alembic.config import Config
        from alembic import command
        alembic_cfg = Config(alembic_config_ini)
        command.stamp(alembic_cfg, 'head')