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'。
{
    factory.registerStorage("Merge", [](const StorageFactory::Arguments & args)
    {
        /** In query, the name of database is specified as table engine argument which contains source tables,
          *  as well as regex for source-table names.
          */
        ASTs & engine_args = args.engine_args;
        if (engine_args.size() != 2)
            throw Exception("Storage Merge requires exactly 2 parameters"
                " - name of source database and regexp for table names.",
                ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
        auto [is_regexp, database_ast] = StorageMerge::evaluateDatabaseName(engine_args[0], args.getLocalContext());
        if (!is_regexp)
            engine_args[0] = database_ast;
        String source_database_name_or_regexp = database_ast->as<ASTLiteral &>().value.safeGet<String>();
        engine_args[1] = evaluateConstantExpressionAsLiteral(engine_args[1], args.getLocalContext());
        String table_name_regexp = engine_args[1]->as<ASTLiteral &>().value.safeGet<String>();
        return StorageMerge::create(
            args.table_id, args.columns, args.comment, source_database_name_or_regexp, is_regexp, table_name_regexp, args.getContext());
    });
}
NamesAndTypesList StorageMerge::getVirtuals() const