Ron <ronljohnsonjr@xxxxxxxxx> 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