Re: Support for RANGE ... PRECEDING windows in OVER

On Fri, Jun 21, 2013 at 3:20 AM, Craig Ringer <craig@2ndquadrant.com> wrote:

On 06/21/2013 05:32 PM, Hitoshi Harada wrote:

> I also later found that we are missing not only notion of '+' or '-',
> but also notion of 'zero value' in our catalog.  Per spec, RANGE BETWEEN
> needs to detect ERROR if the offset value is negative, but it is not
> always easy if you think about interval, numeric types as opposed to
> int64 used in ROWS BETWEEN.

Zero can be tested for with `val = (@ val)` ie `val = abs(val)`. That
should make sense for any type in which the concept of zero makes sense.

Yeah, I mean, it needs to know if offset is negative or not by testing with zero.  So we need "zero value" or "is_negative function" for each type.

Thanks,

--
Hitoshi Harada