`SELECT ... WHERE match(key, '^prefix...')`
should use index similarly to
`SELECT ... WHERE key LIKE 'prefix%'`
}
    };
    WriteBufferFromOwnString buf;
    switch (function)
    {
        case FUNCTION_AND:
            return "and";
        case FUNCTION_OR:
            return "or";
        case FUNCTION_NOT:
            return "not";
        case FUNCTION_UNKNOWN:
            return "unknown";
        case FUNCTION_NOT_IN_SET:
        case FUNCTION_IN_SET:
        {
            buf << "(";
            print_wrapped_column(buf);
            buf << (function == FUNCTION_IN_SET ? " in " : " notIn ");
            if (!set_index)
                buf << "unknown size set";
            else
                buf << set_index->size() << "-element set";
            buf << ")";
            return buf.str();
        }
        case FUNCTION_IN_RANGE:
        case FUNCTION_NOT_IN_RANGE:
        {
            buf << "(";