Subject: Re: Documentation of return values of range functions lower and upper
To: Laurenz Albe <laurenz.albe@cybertec.at>, jani.rahkola@iki.fi,
 pgsql-docs@lists.postgresql.org
References: <160508672127.25505.8356390205508789564@wrigleys.postgresql.org>
 <53ec9f116bea9252d7fa9341e024530553656c42.camel@cybertec.at>
 <16601466752e40543051369fac722c0a200bb4e6.camel@cybertec.at>
From: Fujii Masao <masao.fujii@oss.nttdata.com>
Message-ID: <27d690d8-0987-5f2b-a2da-fc2ec7c19e3c@oss.nttdata.com>
Date: Wed, 18 Nov 2020 22:49:10 +0900
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On 2020/11/12 17:14, Laurenz Albe wrote:
> On Wed, 2020-11-11 at 18:19 +0100, Laurenz Albe wrote:
>>> Table 9.54 in page
>>> https://www.postgresql.org/docs/current/functions-range.html states that the
>>> functions lower and upper return NULL if the requested bound is infinite. If
>>> the element type of the range contains the special values infinity and
>>> -infinity, this is not correct, as those values are returned if explicitly
>>> used as either bound.
>>
>> +1
>>
>> Perhaps it would be better to say
>>
>>    NULL if the range is empty or has no lower/upper bound

I agree this description looks a bit confusing. But according to the section
"Infinite (Unbounded) Ranges" (*1), we already call "lower/upper bound
omitted" just infinite. So I don't think the current description is incorrect.

(*1)
https://www.postgresql.org/docs/devel/rangetypes.html#RANGETYPES-INFINITE

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION