Re: Split daterange into sub periods

Hi,

I'm looking for splitting a daterange into many subperiods following this example:

Base Date: [2018-01-01, 2018-01-31]

overlapped_periods:

1- [ 2018-01-04, 2018-01-06]

2- [ 2018-01-09, 2018-01-12]

3- [ 2018-01-18, 2018-01-19]

I try to get such a result:
1- [ 2018-01-01, 2018-01-03]

2- [ 2018-01-07, 2018-01-08]

3- [ 2018-01-13, 2018-01-17]

4- [ 2018-01-20, 2018-01-31]

The operator '-' does not support this :

SELECT daterange('2018-01-01', '2018-01-31', '[]') - daterange('2018-01-04', '2018-01-06', '[]');

I got this error:
ERROR: result of range difference would not be contiguous

Is there any operators to make the split of daterange?

andreas@[local]:5432/test# \d hmidi
                Table "public.hmidi"
 Column |   Type    | Collation | Nullable | Default
--------+-----------+-----------+----------+---------
 id     | integer   |           | not null |
 d      | daterange |           |          |
Indexes:
    "hmidi_pkey" PRIMARY KEY, btree (id)

andreas@[local]:5432/test# insert into hmidi values (1,'[2018-01-04,2018-01-06]');INSERT 0 1
andreas@[local]:5432/test# insert into hmidi values (2,'[2018-01-09,2018-01-12]');INSERT 0 1
andreas@[local]:5432/test# insert into hmidi values (3,'[2018-01-18,2018-01-19]');INSERT 0 1
andreas@[local]:5432/test# with month as (select s::date from generate_series('2018-01-01'::date, '2018-01-31'::date,'1day'::interval) s), tmp as ( select month.s, case when hmidi.d @> month.s then 1 else NULL end as covered from month left join hmidi on month.s <@ hmidi.d),tmp2 as ( select *, coalesce((sum(case when covered = 1 then 1 else NULL end) over (order by s))+1,1) as p from tmp) select p, min(s), max(s) from tmp2 where covered is null group by p order by p;
 p  |    min     |    max    
----+------------+------------
  1 | 2018-01-01 | 2018-01-03
  4 | 2018-01-07 | 2018-01-08
  8 | 2018-01-13 | 2018-01-17
 10 | 2018-01-20 | 2018-01-31
(4 rows)


Regards, Andreas
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