--
--
-- Forbidding gaps (and overlaps):
--
--
SELECT  room_id, range_agg(booked_during, false)
FROM    reservations
WHERE   room_id = 1
GROUP BY room_id;
ERROR:  range_agg: gap detected between lastRange and currentRange
SELECT  room_id, range_agg(booked_during, false)
FROM    reservations
WHERE   room_id = 6
GROUP BY room_id;
ERROR:  range_agg: overlap detected between lastRange and currentRange
SELECT  room_id, range_agg(booked_during, false)
FROM    reservations
WHERE   room_id NOT IN (1, 6)
GROUP BY room_id;
 room_id |          range_agg          
---------+-----------------------------
       4 | 
       5 | {"[07-01-2018,07-03-2018)"}
       3 | 
       2 | {"[07-01-2018,07-03-2018)"}
       7 | {"[07-01-2018,07-14-2018)"}
(5 rows)

--
--
-- Permitting gaps (but forbidding overlaps):
--
--
SELECT  room_id, range_agg(booked_during, true)
FROM    reservations
WHERE   room_id = 1
GROUP BY room_id;
 room_id |                       range_agg                       
---------+-------------------------------------------------------
       1 | {"[07-01-2018,07-14-2018)","[07-20-2018,07-22-2018)"}
(1 row)

SELECT  room_id, range_agg(booked_during, true)
FROM    reservations
WHERE   room_id = 6
GROUP BY room_id;
ERROR:  range_agg: overlap detected between lastRange and currentRange
SELECT  room_id, range_agg(booked_during, true)
FROM    reservations
WHERE   room_id NOT IN (1, 6)
GROUP BY room_id;
 room_id |          range_agg          
---------+-----------------------------
       4 | 
       5 | {"[07-01-2018,07-03-2018)"}
       3 | 
       2 | {"[07-01-2018,07-03-2018)"}
       7 | {"[07-01-2018,07-14-2018)"}
(5 rows)