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

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.

> 
> -- 
> Angular momentum makes the world go 'round.


-- 
Adrian Klaver
adrian.klaver@aklaver.com