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

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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.





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