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'。
* We could unlock buffer temporary, but it would lead to too many difficulties:
        * - data, that is written, will not be visible for SELECTs;
        * - new data could be appended to buffer, and in case of exception, we must merge it with old data, that has not been written;
        * - this could lead to infinite memory growth.
        */
    Stopwatch watch;
    try
    {
        writeBlockToDestination(block_to_write, DatabaseCatalog::instance().tryGetTable(destination_id, getContext()));
        if (reset_block_structure)
            buffer.data.clear();
    }
    catch (...)
    {
        ProfileEvents::increment(ProfileEvents::StorageBufferErrorOnFlush);
        
        CurrentMetrics::add(CurrentMetrics::StorageBufferRows, block_to_write.rows());
        CurrentMetrics::add(CurrentMetrics::StorageBufferBytes, block_to_write.bytes());
        buffer.data.swap(block_to_write);
        if (!buffer.first_write_time) 
            buffer.first_write_time = current_time;
        
        throw;
    }
    total_writes.rows -= block_rows;
    total_writes.bytes -= block_allocated_bytes_delta;
    UInt64 milliseconds = watch.elapsedMilliseconds();
    LOG_DEBUG(log, "Flushing buffer with {} rows, {} bytes, age {} seconds, took {} ms {}.", rows, bytes, time_passed, milliseconds, (check_thresholds ? "(bg)" : "(direct)"));
}
void StorageBuffer::writeBlockToDestination(const Block & block, StoragePtr table)