Identity modelling (was: dbdebunk 'Quote of Week' comment)

Alexandr Savinov wrote:
[snip]
> In general I think that we lack information on "identtity modeling"
> althoug it is as important as data modeling itself. Identity modeling is
> a separate topic, a dual part for data modeling. In other words, we can
> model identity ignoring object properties. And it may well be rather
> complex model. It will involve entities without properties - only
> identities. The following properties of identity make this task rather
> difficult:
>
> - Identity is distributed among many entites. It can be hierarchical.
> For example, an element of categorization might have several segments
> each specifying relative position. A fully qualified identifier then is
> composed of several identifiers (for example, several primary keys taken
> from different tables - having one primary key is not enough).
>
> - Identity cannot be considered without its scope. For example, a
> physical address is retricted by the scope of one computer, a primary
> key might be restricted by one database etc.
>
> - Logical/physical is a relative characterization rather than absolute.
> Memory handle is really physical for an application program that uses
> it, but it is logical for operating system w.r.t. to absolute offsets
> in physical memory (offset may change while memory handle does not
> change). In this sense all those disputes about lgoical/physical are
> meaningless without specifying the context. Primary key may well be
> viewed as a physical identifier from the point of view of some higher
> level identification mechanism, say, global id. This means that global
> id is permanent while primary key it substitues may change.
>
> - Any identifier is based on some environemnt that provides a coordinate
> system that it uses to produce its own identifiers. In other words, any
> new identification system is based on some lower level identification
> system (environemtn or context) with its scope and structure.
>
> Currently no one model provides anything that would deal with the topic
> of identity modeling. We can model columns and object properties more or
> less successfully. But another side is still in darkness. We have tools
> to implement identification mechanisms ourselves but we do not have a
> theory for that.

This deserves - at least - a thread of it's own. If it would be a /. moderation I'ld have a hard time to choose between 'Insightful' and 'Interesting'.
No time to comment at this time, though :-( Received on Mon Aug 29 2005 - 21:29:35 CEST