`SELECT ... WHERE match(key, '^prefix...')`
should use index similarly to
`SELECT ... WHERE key LIKE 'prefix%'`
return true;
        }
    },
    {
        "globalNullIn",
        [] (RPNElement & out, const Field &)
        {
            out.function = RPNElement::FUNCTION_IN_SET;
            return true;
        }
    },
    {
        "globalNotNullIn",
        [] (RPNElement & out, const Field &)
        {
            out.function = RPNElement::FUNCTION_NOT_IN_SET;
            return true;
        }
    },
    {
        "empty",
        [] (RPNElement & out, const Field & value)
        {
            if (value.getType() != Field::Types::String)
                return false;
            out.function = RPNElement::FUNCTION_IN_RANGE;
            out.range = Range("");
            return true;
        }
    },