Re: "two time periods with only an endpoint in common do not overlap" ???

[Guyren Howe <guyren@xxxxxxxxx>]

I’m a bit confused by this conversation. Open- and closed-ended ranges behave as I would expect.

select tsrange('2016-01-10 17:00', '2016-01-11 17:00', '[)') && tsrange('2016-01-11 17:00', '2016-01-12 17:00', '[]')
false

select tsrange('2016-01-10 17:00', '2016-01-11 17:00', '[]') && tsrange('2016-01-11 17:00', '2016-01-12 17:00', '[]')
true

On Oct 15, 2021, 11:27 -0700, Brian Dunavant <dunavant@xxxxxxxxx>, wrote:

Think of it this way.  When someone says they have a meeting from 1-2 and another from 2-3, do those meetings overlap?  They do not, because we're actually saying the first meeting is from 1:00 through 1:59:59.99999.   The Postgres date ranges are the same way.   The starting point is inclusive, but the ending time is exclusive.   So [1:00,2:00), and [2:00,3:00), do not overlap.

On Fri, Oct 15, 2021 at 2:16 PM Ron <ronljohnsonjr@xxxxxxxxx> wrote:

On 10/15/21 8:59 AM, Adrian Klaver wrote:
> On 10/15/21 06:52, Ron wrote:
>> On 10/14/21 7:02 PM, Adrian Klaver wrote:
>> [snip]
>>> or the third example in the docs:
>>>
>>> SELECT (DATE '2001-02-16', DATE '2001-12-21') OVERLAPS
>>>        (DATE '2001-10-30', DATE '2002-10-30');
>>> Result: true
>>> SELECT (DATE '2001-02-16', INTERVAL '100 days') OVERLAPS
>>>        (DATE '2001-10-30', DATE '2002-10-30');
>>> Result: false
>>> SELECT (DATE '2001-10-29', DATE '2001-10-30') OVERLAPS
>>>        (DATE '2001-10-30', DATE '2001-10-31');
>>> Result: false
>>
>> Why /don't/ they overlap, given that they share a common date?
>
> Per the docs:
>
> https://www.postgresql.org/docs/current/functions-datetime.html
>
> " Each time period is considered to represent the half-open interval start
> <= time < end, unless start and end are equal in which case it represents
> that single time instant."
>
> Which I read as
>
> (DATE '2001-10-29', DATE '2001-10-30') ends at '2001-10-29'
>
> and
>
> (DATE '2001-10-30', DATE '2001-10-31') starts at DATE '2001-10-30'
>
> so no overlap.

I was afraid you were going to say that.  It's completely bizarre, but seems
to be a "thing" in computer science.

--
Angular momentum makes the world go 'round.