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'。
pipe.addSimpleTransform([&](const Block & stream_header)
            {
                return std::make_shared<ExpressionTransform>(stream_header, adding_column_actions);
            });
        }
        if (has_table_virtual_column && !pipe_header.has("_table"))
        {
            ColumnWithTypeAndName column;
            column.name = "_table";
            column.type = std::make_shared<DataTypeString>();
            column.column = column.type->createColumnConst(0, Field(table_name));
            auto adding_column_dag = ActionsDAG::makeAddingColumnActions(std::move(column));
            auto adding_column_actions = std::make_shared<ExpressionActions>(
                std::move(adding_column_dag),
                ExpressionActionsSettings::fromContext(modified_context, CompileExpressions::yes));
            pipe.addSimpleTransform([&](const Block & stream_header)
            {
                return std::make_shared<ExpressionTransform>(stream_header, adding_column_actions);
            });
        }
        
        
        convertingSourceStream(header, metadata_snapshot, aliases, modified_context, modified_query_info.query, pipe, processed_stage);
        pipe.addTableLock(struct_lock);
        pipe.addStorageHolder(storage);
        pipe.addInterpreterContext(modified_context);
    }
    return pipe;
}
StorageMerge::StorageListWithLocks StorageMerge::getSelectedTables(