Change the table comment after created the table is not supported now?
Like mysql : ALTER TABLE [tableName] COMMNET [comment]; 
The sql "ALTER TABLE `system`.tables UPDATE Comment='test' WHERE NAME='t1';" also not supported!!!
My version is '21.9.4.35'。
rows = buffer.data.rows();
    bytes = buffer.data.bytes();
    if (buffer.first_write_time)
        time_passed = current_time - buffer.first_write_time;
    if (check_thresholds)
    {
        if (!checkThresholdsImpl(false, rows, bytes, time_passed))
            return;
    }
    else
    {
        if (rows == 0)
            return;
    }
    buffer.data.swap(block_to_write);
    buffer.first_write_time = 0;
    size_t block_rows = block_to_write.rows();
    size_t block_bytes = block_to_write.bytes();
    size_t block_allocated_bytes_delta = block_to_write.allocatedBytes() - buffer.data.allocatedBytes();
    CurrentMetrics::sub(CurrentMetrics::StorageBufferRows, block_rows);
    CurrentMetrics::sub(CurrentMetrics::StorageBufferBytes, block_bytes);
    ProfileEvents::increment(ProfileEvents::StorageBufferFlush);
    if (!destination_id)
    {
        total_writes.rows -= block_rows;
        total_writes.bytes -= block_allocated_bytes_delta;
        LOG_DEBUG(log, "Flushing buffer with {} rows (discarded), {} bytes, age {} seconds {}.", rows, bytes, time_passed, (check_thresholds ? "(bg)" : "(direct)"));
        return;
    }
    /** For simplicity, buffer is locked during write.