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'。
for (const auto & iterator : database_table_iterators)
    {
        if (filter_by_database_virtual_column)
            database_name_virtual_column->insert(iterator->databaseName());
        while (iterator->isValid())
        {
            StoragePtr storage = iterator->table();
            if (!storage)
                continue;
            if (query && query->as<ASTSelectQuery>()->prewhere() && !storage->supportsPrewhere())
                throw Exception("Storage " + storage->getName() + " doesn't support PREWHERE.", ErrorCodes::ILLEGAL_PREWHERE);
            if (storage.get() != this)
            {
                auto table_lock = storage->lockForShare(query_context->getCurrentQueryId(), settings.lock_acquire_timeout);
                selected_tables.emplace_back(iterator->databaseName(), storage, std::move(table_lock), iterator->name());
                if (filter_by_table_virtual_column)
                    table_name_virtual_column->insert(iterator->name());
            }
            iterator->next();
        }
    }
    if (filter_by_database_virtual_column)
    {
        
        Block virtual_columns_block
            = Block{ColumnWithTypeAndName(std::move(database_name_virtual_column), std::make_shared<DataTypeString>(), "_database")};
        VirtualColumnUtils::filterBlockWithQuery(query, virtual_columns_block, query_context);
        auto values = VirtualColumnUtils::extractSingleValueFromBlock<String>(virtual_columns_block, "_database");
        
        selected_tables.remove_if([&](const auto & elem) { return values.find(std::get<0>(elem)) == values.end(); });