What is a simple and efficient way to find rows with time-interval overlaps in SQL?

Question

I have two tables, both with start time and end time fields. I need to find, for each row in the first table, all of the rows in the second table where the time intervals in

Answer 1

select * from table_1 
right join 
table_2 on 
(
table_1.start between table_2.start and table_2.[end]
or
table_1.[end] between table_2.start and table_2.[end]
or
(table_1.[end] > table_2.start and table_2.[end] is null)
)

EDIT: Ok, don't go for my solution, it perfoms like shit. The "where" solution is 14x faster. Oops...

Some statistics: running on a db with ~ 65000 records for both table 1 and 2 (no indexing), having intervals of 2 days between start and end for each row, running for 2 minutes in SQLSMSE (don't have the patience to wait)

Using join: 8356 rows in 2 minutes

Using where: 115436 rows in 2 minutes

Answer 2

It's sound very complicated until you start working from reverse. Below I illustrated ONLY GOOD CASES (no overlaps)! defined by those 2 simple conditions, we have no overlap ranges if condA OR condB is TRUE, so we going to reverse those: NOT condA AND NOT CondB, in our case I just reversed signs (> became <=)

/*
|--------| A                             \___  CondA: b.ddStart >  a.ddEnd
            |=========| B                /      \____ CondB:  a.ddS >  b.ddE
                          |+++++++++| A         /
*/
--DROP TABLE ran
create table ran ( mem_nbr int, ID int, ddS date, ddE date)
insert ran values  
(100, 1,  '2012-1-1','2012-12-30'),    ----\ ovl
(100, 11, '2012-12-12','2012-12-24'),  ----/
(100, 2, '2012-12-31','2014-1-1'),
(100, 3, '2014-5-1','2014-12-14') ,

(220, 1, '2015-5-5','2015-12-14') ,    ---\ovl
(220, 22, '2014-4-1','2015-5-25') ,    ---/
(220, 3, '2016-6-1','2016-12-16')  

select  DISTINCT a.mem_nbr ,  a.* , '-' [ ], b.dds, b.dde, b.id 
FROM ran a
join ran b  on  a.mem_nbr = b.mem_nbr          -- match by mem#
               AND     a.ID <> b.ID            -- itself
                  AND     b.ddS <= a.ddE        -- NOT    b.ddS >  a.ddE       
                  AND     a.ddS <= b.ddE        -- NOT    a.ddS >  b.ddE   

Answer 3

And what, if you want to analyse such an overlap on a minute precision with 70m+ rows? the only solution i could make up myself was a time dimension table for the join

else the dublicate-handling became a headache .. and the processing cost where astronomical

Answer 4

"solutions from other platforms may be of interest also."

SQL Standard defines OVERLAPS predicate:

Specify a test for an overlap between two events.

<overlaps predicate> ::=
   <row value constructor 1>  OVERLAPS <row value constructor 2> 

Example:

SELECT 1
WHERE ('2020-03-01'::DATE, '2020-04-15'::DATE) OVERLAPS 
      ('2020-02-01'::DATE, '2020-03-15'::DATE) 
-- 1

db<>fiddle demo

Answer 5

SELECT * 
FROM table1,table2 
WHERE table2.start <= table1.end 
AND (table2.end IS NULL OR table2.end >= table1.start)