Re: "thou shalt not conflate meta-data with data"

>> When modeling "John is a person & John is male
>> & male is a gender" which data is meta data?
>> Which data "step[s] outside the language to talk
>> about the language itself" ?
>
> the meta-data would be things like "gender G is of
> varchar(10) type" or "the table representing the predicate
> 'person P has gender G' is called T_Person".

Thus it seems, Morgan's definition that meta data is "data about data" was along the right track, however it was too broad since male is data about John, but male is not considered meta data. Frosty's response that attributes of a table (ie Gender & Age) are examples of meta data was basically correct. And based on your example above, it seems a narrower definition might be: meta data is data that imposes some condition (structure, constraints, significance, etc) upon other data. For example, data for a relation's header might impose the condition that data in tuples represent persons and each value corresponds to predesignated attributes.

> This is from a relational database point of view, I guess you
> could have a system where both the things above are considered
> just as "data". As I said before, the terms "data" and "meta-data"
> are defined only within the context of a system, so you can't
> give an absolute answer.

I would agree (that which is meta data in RM sometimes isn't in XDb). Received on Thu Mar 03 2005 - 03:15:08 CET