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 -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
