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 (required_column == header_column.name)
                    throw Exception("Block structure mismatch in Merge Storage: different types:\n" + before_block_header.dumpStructure()
                                    + "\n" + header.dumpStructure(), ErrorCodes::LOGICAL_ERROR);
            }
        }
    }
}
IStorage::ColumnSizeByName StorageMerge::getColumnSizes() const
{
    auto first_materialized_mysql = getFirstTable([](const StoragePtr & table) { return table && table->getName() == "MaterializedMySQL"; });
    if (!first_materialized_mysql)
        return {};
    return first_materialized_mysql->getColumnSizes();
}
std::tuple<bool , ASTPtr> StorageMerge::evaluateDatabaseName(const ASTPtr & node, ContextPtr context_)
{
    if (const auto * func = node->as<ASTFunction>(); func && func->name == "REGEXP")
    {
        if (func->arguments->children.size() != 1)
            throw Exception("REGEXP in Merge ENGINE takes only one argument", ErrorCodes::BAD_ARGUMENTS);
        auto * literal = func->arguments->children[0]->as<ASTLiteral>();
        if (!literal || literal->value.safeGet<String>().empty())
            throw Exception("Argument for REGEXP in Merge ENGINE should be a non empty String Literal", ErrorCodes::BAD_ARGUMENTS);
        return {true, func->arguments->children[0]};
    }
    auto ast = evaluateConstantExpressionForDatabaseName(node, context_);
    return {false, ast};
}
void registerStorageMerge(StorageFactory & factory)