[sc34wg3] Comments on N448

Lars Marius Garshol sc34wg3@isotopicmaps.org
25 Nov 2003 21:42:09 +0100

Hello Kato-san, and welcome! I'm glad to see that you are now actively
involved in this work.

* Hiroyuki KATO
| * In general, high level query languages must be declarative same as
| SQL or XQuery is. So, add "TMQL must be declarative and must be
| independent of any particular evaluation strtegy." to
| 4. Requirements for the Language or a suitable section.

I think you are right about this, and in fact we used to have half of
that requirement in the document, but we seem to have lost it.

I suggest we add this as item 4 in section 4.1, unless someone is
against it. Robert, what do you think?

| "Declarative" means that answers are specified by properties they
| satisfy, with no refernce to an algorithm for producing them[AHV95].

The standard may define the query results through the application of a
particular algorithm, but I agree that it shouldn't *require* that
algorithm to be used. I think without such a specification it may be
difficult to specify some aspects of how TMQL language features
| * TMQL should support grouping and aggregations functionality.

Again I think you are right, and this is a requirement that just
slipped through the cracks, but really ought to have been in there.
I suggest we add this to section 4.3 as item 7.

| SQL has a GROUPBY clause to support this, Datalog also has this
| introduced by Mumick[MPR90] or Consens[CM90]. XQuery doesn't have an
| explicit GROUPBY expression but has an expressive power with
| implicit GROUPBY semantics[XQuery-issue168].

I think doing this as SQL/Datalog do, or as XQuery does would be
equally acceptable, so long as we have support for it.

| "4.1 Functionality" is briefy described. So, the granuality of
| functionality is different from each of three functionality in 4.1,
| but both AsTMa? and tolog don't mention this, as far as I know.

I'm not sure what you mean by this. tolog has aggregates, but not yet
any grouping support. I don't know about AsTMa? 

Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >