Re: Storing data and code in a Db with LISP-like interface

Neo wrote:
> TopMind, it seems we are slipping back to an endless answer/question
> mode which spawns even more... Since I have asked serveral times, how
> you want to handle the shortcommings in the current RM schema to
> represent that in court judge example (which gets more difficult for
> various types of things in the has hierarchy) and not gotten a
> response,

I missed any messages where RM had difficulty.

> I suggest we put this one side and focus on the simpler food
> judge example which is well within RM's scope; however at least we can
> actually compare methodologies and I can extend that example to
> highlight some features and answer your questions. In addition, Nick
> has posted a Prolog based solution and this would be an excellent
> opportunity to compare three methodologies!
>
> >> The exp's data model is more general than all the data representation methodogies/implementations including Hierarchal, Network, Relational, etc that can be used to create a db (ie runs on computers where the data is non-redundant, thus allowing for efficient data mgmt).
> .
> > How does one objectively measure "general"? They are all potentially representionally equivalent.
>
> While it is theoretically possible for different data models to
> represent the same thing, one has to consider the practicality of doing
> so. Thus theoretically, the Hierarchal Model can represent the the same
> things as the Relational Model, however the further beyond Hierarchal
> Model's scope we get, the more impractical it becomes. Simlarly, it is
> theoretically possible for RM to represent court-judge-type examples,
> however they starts to become impractical. Factors that may be involved
> in measuring generalness are 1) when does the data model start to
> incur redundancies 2) when does the data model start to incur NULLs

"Null" (or empty) are often just space-holders in RM. They don't have to take up any actual storage. It just like saying that there is no corresponding attribute for a given cell or question.

> 3) when do the modelling methods change 4) constriants due to the
> model itself.
>
> For example, the exp db's model has no schema constraints as required
> by RM. Just on this alone, it is probably IMPOSSIBLE for RM to ever be
> as general/flexible.

Huh? Constraints are a bonus feature, not manditory in RM. Stop thinking that RM == Oracle. Oracle is not a good example of nimble/dynamic RM.

> In addition, RMDB implementations have additional
> hardware related constraints such as data types,

Again, this is vendor specific and not required by RM. SqLite is an example where explicit types are optional.

> where as the exp db
> does not. Exp db's generalness/flexibility and better abstraction of
> the hardware layer comes at the cost of resources such as memory,
> processing time, etc. (Note: even though the exp db's data model has no
> constraints and user does not specify a schema, this does not prevent
> the db from representing things in a non-redundant manner, which allows
> for efficient data mgmt - ie queries, updates, etc)
>
> Because I know both the exp and RM data models, it is easy for me to
> see why exp data model is more general/flexible; however I don't not
> want to discuss it's details currently. An alternate way to measure the
> generalness/flexibility/scope of a tool is by verifying what range of
> problems/applications the tool is practical for.
>
> For example, the scope/generalness/flexibility of a size 5mm socket,
> might be nuts from 4.95 to 5.05 mm. If we use a hammer, the socket
> might work from 4.9 to 5.1 mm but it is slightly impractical. Notice
> the method has changed, we now need to hammer. If we now use a
> sledgehammer and safety glasses, the socket might work for 4.8 to 5.2
> mm. Notice the method has changed again.
>
> With respect to a data models, generalness/scope/flexibility is the
> range of things that can be represented in a practical manner. For
> example, thus far the exp db examples have shown it can represent
> tables, hierarchies, matrixes and some variable structures. But I
> haven't yet seen anyone successfully represent data in exp db's court
> judge example.

Again, I missed RM breaking down.

-T- Received on Thu Apr 27 2006 - 07:31:40 CEST