Sum varighed af overlappende perioder med prioritet ved at ekskludere selve overlapningen

Opdater Min oprindelige løsning var ikke korrekt. Konsolideringen af ​​intervaller kan ikke håndteres i et almindeligt vindue. Jeg forvirrede mig selv ved at bruge det samme navn, trange , og glemmer, at vinduet er over kilderækkerne i stedet for resultatrækkerne. Se venligst den opdaterede SQL Fiddle med den fulde forespørgsel samt en tilføjet post for at illustrere problemet.

Du kan forenkle kravet om overlapning samt identificere huller og øer ved hjælp af PostgreSQL-områdetyper .

Følgende forespørgsel er bevidst udførlig for at vise hvert trin i processen. En række trin kan kombineres.

SQL Fiddle

Tilføj først en inkluderende [start, end] rækkevidde til hver post.

with add_ranges as (
  select id, name, tsrange(start, "end", '[]') as t_range
    from activities
), 

 id | name |                    t_range                    
----+------+-----------------------------------------------
  1 | A    | ["2018-01-09 17:00:00","2018-01-09 20:00:00"]
  2 | A    | ["2018-01-09 18:00:00","2018-01-09 20:30:00"]
  3 | B    | ["2018-01-09 19:00:00","2018-01-09 21:30:00"]
  4 | B    | ["2018-01-09 22:00:00","2018-01-09 23:00:00"]
(4 rows)

Identificer overlappende områder som bestemt af && operatør og marker begyndelsen af ​​nye øer med en 1 .

mark_islands as (
  select id, name, t_range,
         case
           when t_range && lag(t_range) over w then 0
           else 1
         end as new_range
    from add_ranges
  window w as (partition by name order by t_range)
),

 id | name |                    t_range                    | new_range 
----+------+-----------------------------------------------+-----------
  1 | A    | ["2018-01-09 17:00:00","2018-01-09 20:00:00"] |         1
  2 | A    | ["2018-01-09 18:00:00","2018-01-09 20:30:00"] |         0
  3 | B    | ["2018-01-09 19:00:00","2018-01-09 21:30:00"] |         1
  4 | B    | ["2018-01-09 22:00:00","2018-01-09 23:00:00"] |         1
(4 rows)

Nummerer grupperne baseret på summen af ​​new_range i navn .

group_nums as (
  select id, name, t_range, 
         sum(new_range) over (partition by name order by t_range) as group_num
    from mark_islands
),

 id | name |                    t_range                    | group_num 
----+------+-----------------------------------------------+-----------
  1 | A    | ["2018-01-09 17:00:00","2018-01-09 20:00:00"] |         1
  2 | A    | ["2018-01-09 18:00:00","2018-01-09 20:30:00"] |         1
  3 | B    | ["2018-01-09 19:00:00","2018-01-09 21:30:00"] |         1
  4 | B    | ["2018-01-09 22:00:00","2018-01-09 23:00:00"] |         2

Gruppér efter navn, gruppe_nummer for at få den samlede tid brugt på øen samt et komplet t_range skal bruges i overlapningsfradrag.

islands as (
  select name,
         tsrange(min(lower(t_range)), max(upper(t_range)), '[]') as t_range,
         max(upper(t_range)) - min(lower(t_range)) as island_time_interval
    from group_nums
   group by name, group_num
),

 name |                    t_range                    | island_time_interval 
------+-----------------------------------------------+----------------------
 A    | ["2018-01-09 17:00:00","2018-01-09 20:30:00"] | 03:30:00
 B    | ["2018-01-09 19:00:00","2018-01-09 21:30:00"] | 02:30:00
 B    | ["2018-01-09 22:00:00","2018-01-09 23:00:00"] | 01:00:00
(3 rows)

For kravet om at tælle overlapningstid mellem A beskeder og B meddelelser, find forekomster af, hvornår en A besked overlapper en B besked, og brug * krydsoperator for at finde krydset.

priority_overlaps as (
  select b.name, a.t_range * b.t_range as overlap_range
    from islands a
    join islands b
      on a.t_range && b.t_range
     and a.name = 'A' and b.name != 'A'
),

 name |                 overlap_range                 
------+-----------------------------------------------
 B    | ["2018-01-09 19:00:00","2018-01-09 20:30:00"]
(1 row)

Sum den samlede tid for hver overlapning med navn .

overlap_time as (
  select name, sum(upper(overlap_range) - lower(overlap_range)) as total_overlap_interval
    from priority_overlaps
   group by name
),

 name | total_overlap_interval 
------+------------------------
 B    | 01:30:00
(1 row)

Beregn den samlede tid for hvert navn .

island_times as (
  select name, sum(island_time_interval) as name_time_interval
    from islands
   group by name
)

 name | name_time_interval 
------+--------------------
 B    | 03:30:00
 A    | 03:30:00
(2 rows)

select i.name,
       i.name_time_interval - coalesce(o.total_overlap_interval, interval '0') as duration
  from island_times i
  left join overlap_time o
    on o.name = i.name
;

 name | duration 
------+----------
 B    | 02:00:00
 A    | 03:30:00
(2 rows)