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

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От Hitoshi Harada
Тема Re: Support for RANGE ... PRECEDING windows in OVER
Дата
Msg-id CAP7QgmkfHGnzXderNj8m4UsgSWZj5a6A+X5vrfw7owx9yrNJ=A@mail.gmail.com
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Ответ на Re: Support for RANGE ... PRECEDING windows in OVER  (Craig Ringer <craig@2ndquadrant.com>)
Ответы Re: Support for RANGE ... PRECEDING windows in OVER  (ian link <ian@ilink.io>)
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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

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