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

From: Craig Ringer <craig(at)2ndquadrant(dot)com>
To: Hitoshi Harada <umi(dot)tanuki(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Support for RANGE ... PRECEDING windows in OVER
Date: 2013-06-21 10:20:29
Message-ID: 51C428ED.10902@2ndquadrant.com
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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.

Thanks for the warning on that issue.

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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