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'。
}
    if (filter_by_table_virtual_column)
    {
        
        Block virtual_columns_block = Block{ColumnWithTypeAndName(std::move(table_name_virtual_column), std::make_shared<DataTypeString>(), "_table")};
        VirtualColumnUtils::filterBlockWithQuery(query, virtual_columns_block, query_context);
        auto values = VirtualColumnUtils::extractSingleValueFromBlock<String>(virtual_columns_block, "_table");
        
        selected_tables.remove_if([&](const auto & elem) { return values.find(std::get<3>(elem)) == values.end(); });
    }
    return selected_tables;
}
DatabaseTablesIteratorPtr StorageMerge::getDatabaseIterator(const String & database_name, ContextPtr local_context) const
{
    auto database = DatabaseCatalog::instance().getDatabase(database_name);
    auto table_name_match = [this, database_name](const String & table_name_) -> bool
    {
        if (source_databases_and_tables)
        {
            if (auto it = source_databases_and_tables->find(database_name); it != source_databases_and_tables->end())
                return it->second.count(table_name_);
            else
                return false;
        }
        else
            return source_table_regexp->match(table_name_);
    };
    return database->getTablesIterator(local_context, table_name_match);
}
StorageMerge::DatabaseTablesIterators StorageMerge::getDatabaseIterators(ContextPtr local_context) const