From: | Isaac Morland <isaac(dot)morland(at)gmail(dot)com> |
---|---|
To: | Greg Sabino Mullane <htamfids(at)gmail(dot)com> |
Cc: | Rob Foehl <rwf(at)loonybin(dot)net>, pgsql-general(at)lists(dot)postgresql(dot)org |
Subject: | Re: Finding "most recent" using daterange |
Date: | 2024-05-22 15:13:12 |
Message-ID: | CAMsGm5e5=YcjaUGQogkxMqrj9_beuSmVOrXTAuQPsBdmkbZPSA@mail.gmail.com |
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Lists: | pgsql-general |
On Wed, 22 May 2024 at 10:15, Greg Sabino Mullane <htamfids(at)gmail(dot)com>
wrote:
> This is a good candidate for a window function. Also note that nulls
> already get sorted correctly by the DESC so no need to get 'infinity'
> involved, although you could write 'DESC NULLS FIRST' to be explicit about
> it.
>
> with x as (select *, row_number() over (partition by id order by
> upper(dates) desc, lower(dates) desc) from example)
> select id,value,dates from x where row_number = 1;
>
Don’t you need NULLS LAST for the lower bounds? There NULL means something
closer to -infinity and should appear after the non-NULL values in a
descending sort.
Actually it strikes me that this sorting issue could be a reason to avoid
NULL bounds on ranges and prefer the use of +/-infinity if the underlying
data type supports it.
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