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From: Isaac Morland <[email protected]>
To: Greg Sabino Mullane <[email protected]>
Cc: Rob Foehl <[email protected]>
Cc: [email protected]
Subject: Re: Finding "most recent" using daterange
Date: Wed, 22 May 2024 11:13:12 -0400
Message-ID: <CAMsGm5e5=YcjaUGQogkxMqrj9_beuSmVOrXTAuQPsBdmkbZPSA@mail.gmail.com> (raw)
In-Reply-To: <CAKAnmmLBxrQ0n4+BPb_xBQKrDRoiq4eSKdQYDbnmo7KTQVFuRg@mail.gmail.com>
References: <[email protected]>
	<CAKAnmmLBxrQ0n4+BPb_xBQKrDRoiq4eSKdQYDbnmo7KTQVFuRg@mail.gmail.com>

On Wed, 22 May 2024 at 10:15, Greg Sabino Mullane <[email protected]>
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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