Re: One Ring to Bind Them

Anthony W. Youngman wrote:
> In message <c9GdnW9YiKJkSlDd4p2dnA_at_comcast.com>, Laconic2
> <laconic2_at_comcast.net> writes

 >
> Yes, but relational formalises metadata INTO data.

No formalization is needed; metadata is data. It's just data with a different domain, but there's no reason to think it obeys different laws or requires different structure.

> Once it's in an RDBMS
> it's no longer metadata, because the rdbms doesn't understand any
> meaning in it and can't take advantage of that meaning so it's just data.

I'm confused. How does placing it in an RDBMS make it no longer metadata? The system catalog (metadata - data about your data) can be represented relationally (or as XML if you're feeling masochistic).

How does the RDBMS "understand" no meaning in it? And how do other DBMSs "understand" meaning? The constraints and relation definitions of the metadata are as much meaning as the RDBMS can have.

> The ordering in a list is metadata. Convert that into a set to put into
> an rdbms and ORDER is now just a meaningless (as far as the db engine is
> concerned) bit of data.

No, in that case order is gone, vanished. If you don't state it, the RDBMS doesn't know about it. On the other hand, it doesn't assume anything either. Order is easily represented, and again if you're masochistic, you can store a list-typed attribute.

> That's where MV and OO fundamentally differ. They try to *avoid*
> converting metadata to data, so that the db engine can be intelligent
> and take advantage of it to optimise things.

So by treating metadata as something other than data (what would that be?), they can be intelligent and optimize? Intelligent how? Optimize what?

• erk