Re: how do you write aggregate function

On Sun, Mar 09, 2008 at 11:40:47AM -0500, Justin wrote:
> I got the aggregate function for weighted average done.   I finely left
> alone for more than 10 minutes  to actual get it written.  It takes 2
> value input  Weight and the Value.  it will sum the weighted entries to
> create the constant then does the normal formula, but does not
> percentage number but averaged number.  A simple change on the return
> line it can do percentages.

If you're looking for performance, ISTM the best option would be to
simply accumulate the weights and value*weight as you go and do a
division at the end. That seems likely to beat any implementation
involving array_append.

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> Please line up in a tree and maintain the heap invariant while
> boarding. Thank you for flying nlogn airlines.