Re: Temporal Databases

On Feb 24, 2006, at 3:34 , Rodrigo Sakai wrote:

>   I'm focus on temporal databases (not temporary), and I want to
> know if anyone here is studying this tecnologies too. So, we can
> exchange knowlegment. Specifically, anyone who is trying to
> implement on postgresql the aspect of time (temporal).
>   These researches are lead by Richard Snodgrass. So, anyone who
> have something to share, please contact me!

Nice to meet you, Rodrigo. This is an area that I hope to do some
work on as well.

Another resource that you may find useful is Date, Darwen, and
Lorentzos' "Temporal Data and the Relational Model" which starts from
temporal data in particular and proposes a more generalized
"interval"  data type constructor. Lorentzos has also published some
articles on IXSQL[2] which you may find interesting in its extensions
to SQL in particular, rather than the relational model.

You may also be interested to know there is an no-longer documented
tinterval type in Postgres. I don't believe it's even been tested in
recent years, but you may want to look at its implementation.

Michael Glaesemann
grzm myrealbox com

[1](http://www.amazon.com/gp/product/1558608559/)
[2] Nikos A. Lorentzos and Yannis G. Mitsopoulos, "SQL Extension for
Interval Data",  IEEE Transactions On Knowledge And Data
Engineering,  Vol.  9,  No.  3,  May/June  1997