2008/7/5 Martijn van Oosterhout <[EMAIL PROTECTED]>: > On Sat, Jul 05, 2008 at 07:04:29PM +0900, H.Harada wrote: >> Hi, >> >> As I proposed a month before, I am working on window function. > > Very nice! > >> http://umitanuki.net/pgsql/wfv01/design.html >> >> The problem is, as written in the "Things to discussed" section of the >> document, how you define window functions (e.g. RANK()). My idea is to >> treat them as specialized functions such as SET OF functions and mark >> it in pg_proc. But this doesn't resolve RANK() boundary problem. > > Actually, I would make RANK() and ROW_NUMBER() act more like > aggregates. ISTM you have two kinds of window functions: > > - aggregation: a result is calculated over a set and the result copied > across all the rows. > - order depenadant: same as above, but the result is different for each > row.
So I agree the definition of these two types. > I think you could make the latter work using the current aggregation > setup, just by calling the final_func for each row rather than just > once at the end. How do you know which type of two above is used in the same SQL syntax? -- Hitoshi Harada -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
