Thread: Recursive temporal query
Hi,
I am trying to run a recursive cte query on temporal data.
I attach the starting set (temp_station) and the solution set (temp_solution)
A user visits many stations in random order.
They can enter a station many times but they only exit once.
After they enter a station X, they can enter other stations or exit other stations, i.e. a station entry/exit can fully contain other stations) but eventually they will exit station X (these are invalid visits to other stations within an entry/exit context for a single station.)
They can validly visit a station multiple times but these visits must not overlap with each other.
The objective is to list the earliest entry time and matching exit time for each valid visit to a station according to the rules above.
My attempt below doesn't recurse and I can't understand what I need to do here. Can anyone shed some light on this?
Regards
Liam
--drop table temp_station;
create table temp_station
(
station_id int
,movement_direction varchar(5)
,event_tick char(3)
,event_time timestamp with time zone
);
delete from temp_station;
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (1, 'enter', 't01', '2012-10-18 10:23:31');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (1, 'enter', 't02', '2012-10-18 10:31:42');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (1, 'enter', 't03', '2012-10-18 10:41:41');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (1, 'exit', 't04', '2012-10-18 10:48:34');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (2, 'enter', 't05', '2012-10-18 10:54:57');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (2, 'exit', 't06', '2012-10-18 11:01:35');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (3, 'enter', 't07', '2012-10-18 11:10:52');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (3, 'enter', 't08', '2012-10-18 11:20:50');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (4, 'enter', 't09', '2012-10-18 11:29:56');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (3, 'enter', 't10', '2012-10-18 11:37:53');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (7, 'exit', 't11', '2012-10-18 11:44:42');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (3, 'exit', 't12', '2012-10-18 11:53:14');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (4, 'enter', 't13', '2012-10-18 12:02:59');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (4, 'enter', 't14', '2012-10-18 12:12:11');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (4, 'exit', 't15', '2012-10-18 12:20:29');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (2, 'enter', 't16', '2012-10-18 12:26:57');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (2, 'enter', 't17', '2012-10-18 12:34:12');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (9, 'exit', 't18', '2012-10-18 12:40:10');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (2, 'exit', 't19', '2012-10-18 12:48:29');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (5, 'enter', 't20', '2012-10-18 12:54:37');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (5, 'exit', 't21', '2012-10-18 13:00:42');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (6, 'enter', 't22', '2012-10-18 13:06:09');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (6, 'enter', 't23', '2012-10-18 13:15:47');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (6, 'exit', 't24', '2012-10-18 13:23:34');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (6, 'enter', 't25', '2012-10-18 13:29:22');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (6, 'enter', 't26', '2012-10-18 13:37:27');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (5, 'exit', 't27', '2012-10-18 13:45:02');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (6, 'exit', 't28', '2012-10-18 13:53:44');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (7, 'enter', 't29', '2012-10-18 14:00:09');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (7, 'enter', 't30', '2012-10-18 14:08:45');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (8, 'enter', 't31', '2012-10-18 14:14:12');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (8, 'exit', 't32', '2012-10-18 14:20:20');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (7, 'exit', 't33', '2012-10-18 14:28:23');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (2, 'enter', 't34', '2012-10-18 14:35:43');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (2, 'exit', 't35', '2012-10-18 14:44:34');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (8, 'enter', 't36', '2012-10-18 14:51:26');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (8, 'enter', 't37', '2012-10-18 14:59:08');
insert into temp_station (station_id, movement_direction, event_tick, event_time) values (8, 'exit', 't38', '2012-10-18 15:06:10');
--drop table temp_solution;
create table temp_solution
(
station_id int
,movement_direction varchar(5)
,event_tick char(3)
,event_time timestamp with time zone
);
delete from temp_solution;
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (1, 'enter', 't01', '2012-10-18 10:23:31');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (1, 'exit', 't04', '2012-10-18 10:48:34');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (2, 'enter', 't05', '2012-10-18 10:54:57');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (2, 'exit', 't06', '2012-10-18 11:01:35');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (3, 'enter', 't07', '2012-10-18 11:10:52');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (3, 'exit', 't12', '2012-10-18 11:53:14');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (4, 'enter', 't13', '2012-10-18 12:02:59');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (4, 'exit', 't15', '2012-10-18 12:20:29');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (2, 'enter', 't16', '2012-10-18 12:26:57');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (2, 'exit', 't19', '2012-10-18 12:48:29');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (5, 'enter', 't20', '2012-10-18 12:54:37');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (5, 'exit', 't21', '2012-10-18 13:00:42');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (6, 'enter', 't22', '2012-10-18 13:06:09');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (6, 'exit', 't24', '2012-10-18 13:23:34');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (6, 'enter', 't25', '2012-10-18 13:29:22');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (6, 'exit', 't28', '2012-10-18 13:53:44');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (7, 'enter', 't29', '2012-10-18 14:00:09');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (7, 'exit', 't33', '2012-10-18 14:28:23');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (2, 'enter', 't34', '2012-10-18 14:35:43');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (2, 'exit', 't35', '2012-10-18 14:44:34');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (8, 'enter', 't36', '2012-10-18 14:51:26');
insert into temp_solution (station_id, movement_direction, event_tick, event_time) values (8, 'exit', 't38', '2012-10-18 15:06:10');
with recursive
enter_event as
(
select row_number() over(order by event_time) as rownum, *
from temp_station
where movement_direction = 'enter'
--and station_id in (7, 8)
)
,exit_event as
(
select row_number() over(order by event_time) as rownum, *
from temp_station
where movement_direction = 'exit'
--and station_id in (7, 8)
)
,event_period as
(
select a.rownum, a.station_id, a.event_tick as start_tick, b.event_tick as end_tick, a.event_time as start_time, b.event_time as end_time
from enter_event a
join
exit_event b
on a.station_id = b.station_id
-- entry always before exit
and a.event_time < b.event_time
)
,dtr (rownum, station_id, start_tick, end_tick, start_time, end_time) as
(
select rownum, station_id, start_tick, end_tick, start_time, end_time
from event_period
where start_tick = (select min(start_tick) from event_period)
union all
select a.rownum, a.station_id, a.start_tick, a.end_tick, a.start_time, b.end_time
from event_period a
,dtr b
where a.end_time < b.start_time
and a.start_time < a.end_time
and b.start_time < b.end_time
)
select * from dtr