[tmql-wg] Result set requirements

Robert Barta rho@bigpond.net.au
Tue, 16 Mar 2004 10:46:39 +1000

On Mon, Mar 15, 2004 at 07:35:03PM +0100, Lars Marius Garshol wrote:
> | Another consideration in this context is 'typing'. XQuery has done
> | that to quite some extent and I know that many people in the
> | database community take that quite seriously for an excellent means
> | to arrive at some performance.
> As indeed they should; though it should be noted that there can be
> many approaches to typing. tolog doesn't have explicit typing in the
> language,

I think it has explicit typing. All predicates have predefined
profiles. General assocs have them

     some_assoc (player : role, player : role)

and predefined ones have this because they are defined.

But I am not talking (writing actually) about types in the sense of
the implementation (what kind of item in terms of TMDM), but typing
in an application-specific sense.

In XQuery there are not only those types of WXS (the predefined ones,
number, integer, ....), but also this [ not real syntax ]

   element Book := ( element Title, element Author )

This 'typing' gives queries a boost but requires a strong mechanism to
define the type. In the TM area this would be the task of an ontology
language. I do not see this coming with TMCL.

> yet it is sufficiently amenable to analysis that the current
> tolog implementation in the OKS can infer the possible types of every
> variable used in a query.

Without application-specific typing this is straightforward, yes.