| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Robert James <srobertjames(at)gmail(dot)com> |
| Cc: | Postgres General <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Relational Algebra and Aggregate Functions |
| Date: | 2009-07-27 18:45:45 |
| Message-ID: | 1248720345.18098.33.camel@monkey-cat.sm.truviso.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-general |
On Sun, 2009-07-26 at 15:36 -0400, Robert James wrote:
> I'm working on improving my background database theory, to aid in
> practice. I've found learning relational algebra to be very helpful.
> One thing which relational algebra doesn't cover is aggregate
> functions. Can anyone recommend any papers or web pages which provide
> some good theoretical background for aggregate functions?
When it comes to relational theory, C.J. Date is a good author. "An
Introduction To Database Systems" covers pretty much everything.
There's a formal definition of a relational algebra (including
SUMMARIZE, which is the authors' version of an aggregate operator)
defined with only two operators here:
http://thethirdmanifesto.com/
(look for "Appendix A")
Although Appendix A is not easy to understand without some basic
familiarity with the authors' other works.
Regards,
Jeff Davis
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Bill Moran | 2009-07-27 19:41:15 | Re: Running vacuumdb -a taking too long |
| Previous Message | Tom Lane | 2009-07-27 17:49:41 | Re: Calculating the difference between timetz values |