1,3
2,5
4,6
9,14
10,11
12,13

ultimately, I want the results to be

1,6,3
9,14,3

where the third value is the count of the number of overlapping subintervals composing the interval.

Doing the blind approach leads to a runaway expansion that terminates after a recursive depth of 100. That makes sense because this syntax is geared toward expanding - that is what the join does. Actually I suppose it is really the UNION ALL that expands…

I need to do a cross product of the above, eliminating the duplicates: the six instances of the interval and itself, e.g. (1,3,1,3) as well as one of (1,3,2,5), (2,5,1,3). That leaves 15 cross product rows. Then taking the smallest of the first coordinate and the largest of the second, (1,3,2,5) => (1,5) for example, and applying the overlap check I would get four rows that look like the original table:

1,5
2,6
9,14
9,14

Then I need to do the cross product, duplicate elimination, etc. on that set of rows.

Continuing until there are a set of intervals with no overlaps. So this recursions needs to result in a smaller number of rows with each go-round.

I’ll include my code in case anyone wants to try it and supply (I hope) an obvious fix that I just can’t see. It is like I need a set difference function rather than union… and outer joins are not allowed.

TIA!
dc

Code follows:

CREATE TABLE TimeIntervals (
t0 int not null,
t1 int not null,
intcnt int not null
)

INSERT INTO TimeIntervals
(t0, t1, intcnt)
VALUES
(1,3,1)

INSERT INTO TimeIntervals
(t0, t1, intcnt)
VALUES
(2,5,1)

INSERT INTO TimeIntervals
(t0, t1, intcnt)
VALUES
(4,6,1)

INSERT INTO TimeIntervals
(t0, t1, intcnt)
VALUES
(9,14,1)

INSERT INTO TimeIntervals
(t0, t1, intcnt)
VALUES
(10,11,1)

INSERT INTO TimeIntervals
(t0, t1, intcnt)
VALUES
(12,13,1)

WITH CollapsedTimeIntervals (t0, t1, intcnt)
AS
(
– Anchor member definition
select CASE WHEN I.t0 I.s1 THEN I.t1 ELSE I.s1 END AS t1,
newIntcnt
from (
select T.t0 AS t0, T.t1 AS t1, S.t0 AS s0, S.t1 AS s1, T.intcnt 1 AS newIntcnt
from TimeIntervals T, TimeIntervals S
where T.t0 != S.t0 and T.t1 != S.t1
and T.t0 = T.t0 AND S.t0 = T.t0 AND S.t1 = S.t0 AND T.t0 = S.t0 AND T.t1 I.s1 THEN I.t1 ELSE I.s1 END AS t1,
newIntcnt
from (
select T.t0 AS t0, T.t1 AS t1, S.t0 AS s0, S.t1 AS s1, T.intcnt 1 AS newIntcnt
from TimeIntervals T, TimeIntervals S
where T.t0 != S.t0 and T.t1 != S.t1
and T.t0 = T.t0 AND S.t0 = T.t0 AND S.t1 = S.t0 AND T.t0 = S.t0 AND T.t1