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'。
{
    try
    {
        checkStackSize();
    }
    catch (Exception & e)
    {
        e.addMessage("while getting table iterator of Merge table. Maybe caused by two Merge tables that will endlessly try to read each other's data");
        throw;
    }
    DatabaseTablesIterators database_table_iterators;
    
    if (!database_is_regexp)
        database_table_iterators.emplace_back(getDatabaseIterator(source_database_name_or_regexp, local_context));
    
    else
    {
        auto databases = DatabaseCatalog::instance().getDatabases();
        for (const auto & db : databases)
        {
            if (source_database_regexp->match(db.first))
                database_table_iterators.emplace_back(getDatabaseIterator(db.first, local_context));
        }
    }
    return database_table_iterators;
}
void StorageMerge::checkAlterIsPossible(const AlterCommands & commands, ContextPtr local_context) const