Re: Time varying referential integrity

On Dec 27, 2003, at 8:06 PM, Joe Conway wrote:

> Mike Mascari wrote:
>> but not 07-Temporal. Is that right? From a cursory search on temporal
>> support, it appears that there should be a 07-SQL/Temporal group.
>
> Your correct -- I didn't realize that it was its own spec. A little
> googling found me this though:
> http://www.jtc1sc32.org/sc32/jtc1sc32.nsf/Attachments/
> 5A5731749C30132388256A5B0044557A/$FILE/32N0651.PDF

This document is dated 2001-05-29. For some more recent information on
the Temporal-SQL proposal, you can check out Hugh Darwen & C.J. Date's
"Overview and Analysis of TSQL2" (draft dated 2003-09-3)
<http://www.hughdarwen.freeola.com/TheThirdManifesto.web/OnTSQL2.pdf>
Hugh Darwen, of IBM UK, has been an active contributor to SQL
standards, in particular regarding TSQL. According to this "Overview",

"[T]ime ran out toward the end of 2001, when─since no vendor had made
any such move, and the committee had therefore done no further work on
the project to develop Part 7 of the standard─ISO's own bylaws led to
that project being canceled altogether. At the time of writing,
therefore, the working draft document mentioned above ("Part 7:
SQL/Temporal") is in limbo."

Darwen & Date's "Overview" refers to a book they've written, together
with Nikos A. Lorentzos, called "Temporal Data and the Relational
Model" (ISBN 1-55860-855-9) proposing a method of working discrete
point intervals in general (including temporal data in particular).
Hugh Darwen's summary of the book is available at
<http://www.hughdarwen.freeola.com/TheThirdManifesto.web/
TemporalData.pdf>

So right now, it appears the field is pretty open for temporal
implementations. It doesn't look like there's much movement on the ISO
front right now. It's potentially an opportunity for PostgreSQL to
implement something pretty cutting edge. I'm interested in this area,
but have no C coding skills. Any recommendations for getting started on
C? I've also thought there might be some crossover between
discrete-point-interval support and work done for GIS, but I haven't
looked at this very closely yet.

Michael Glaesemann
grzm myrealbox com