Data modelling tools and vendors

It is important to point out that a data modelling tool (I mean, a decent and correct tool) should support at least logical and physical modelling. A tool that one can use to create database schema or database design is DEFINITELY not a data modelling tool, but a database development tool.

I found this link very useful: http://www.databaseanswers.org/modelling_tools.htm
And this link actually is quite updated on the most recent modelling tools.

For enterprise users, Erwin, IDA (previously RDA), MS Visio, Sybase Power Designer and Data Architect, and Oracle tools are the most relevant from the list. I believe SAS also has its tools to support certain level of data modelling.

There is no need to compare these tools. But there are few things to be in mind if you are inspecting data modelling tools.

First, a data modelling tool can be able to support different type of models, such as conceptual model, logical model, and physical model. The typical database theory tells that one should start from conceptual modelling and move down to logical models and then to physical data models.

Second, UML modelling or diagramming is not data modelling. Creating UML elements and show some diagrams (Visio is a good example here) are not modelling but creating sketches. Data modelling requires one to create entities, relationships, attributes, keys, etc. (I listed them in a previous note) and the right data modelling tool should keep the metadata in the data models. Creating diagrams is a small part of data modelling. When the data model gets complicated, it is impossible to show the details in the diagram. That's the time when you need to use the modelling tool to keep the design details.

Third, most of these data modelling tools only provide functionality and do not have any model content. This is absolutely OK. Data modelling is a process of designing intellectual properties. There have been a few vendors of data model content, such as IBM industry model, Teradata model, SAS data model, etc. For small and medium size enterprises, I believe it is quite OK to just take Silverstone's book (the data model resource book, VOL I, II, and III) and copy some part of the content into the modelling tool.

Fourth, I believe that vendors are quite important for data modelling tools in large enterprises. One thing is that when your developers at the company work on a model and find out something wrong in the modelling tool, a good vendor will be able to provide sufficient consultancy support in time. The second thing is that mange large enterprises tend to tailor the modelling tool to have its own "scar" on the assets created by the tool. This requires a close relationship between vendors and users.

So, this is about data modelling tools and vendors. I will write something about useful books, references and resources on data modelling in the coming post....