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

Ron <ronljohnsonjr@gmail.com> writes:
> On 10/14/21 7:02 PM, Adrian Klaver wrote:
>> 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?

They don't.  Per the fine manual [1]:

    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. This means for instance that two
    time periods with only an endpoint in common do not overlap.

            regards, tom lane

[1] https://www.postgresql.org/docs/current/functions-datetime.html