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 <ronljohnso...@gmail.com> 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. > > >
