Road lifecycles: Partition rows into groups

Question

I have a constr_events table:

create table constr_events
   (    
    event_id number(4) not null unique,
    road_id number(4) not null,
    constr_date date not null,
    reset_condition number(9,2) not null
   ) ;
insert into constr_events (event_id, road_id, constr_date, reset_condition) values (1,400,to_date('2016-11-01','YYYY-MM-DD'),1);
insert into constr_events (event_id, road_id, constr_date, reset_condition) values (2,500,to_date('2009-11-01','YYYY-MM-DD'),1);
insert into constr_events (event_id, road_id, constr_date, reset_condition) values (3,500,to_date('2031-11-01','YYYY-MM-DD'),1);
select
    event_id,
    road_id,
    to_char(constr_date,'YYYY-MM-DD') as constr_date_formatted,
    reset_condition
from
    constr_events
order by
    road_id,
    constr_date;

  EVENT_ID    ROAD_ID CONSTR_DATE_FORMATTED  RESET_CONDITION
---------- ---------- ---------------------  ---------------
         1        400 2016-11-01                           1

         2        500 2009-11-01                           1
         3        500 2031-11-01                           1

---

And a road_insp table:

create table road_insp
   (    
    insp_id number(4) not null unique,
    road_id number(4) not null,
    insp_date date not null, 
    condition number(9,2) not null
   ) ;
insert into road_insp (insp_id, road_id, insp_date, condition) values (40,400,to_date('1960-05-01','YYYY-MM-DD'),.8);
insert into road_insp (insp_id, road_id, insp_date, condition) values (41,400,to_date('2009-05-01','YYYY-MM-DD'),.3);
insert into road_insp (insp_id, road_id, insp_date, condition) values (42,400,to_date('2012-05-01','YYYY-MM-DD'),.3);
insert into road_insp (insp_id, road_id, insp_date, condition) values (43,400,to_date('2015-05-01','YYYY-MM-DD'),.2);
insert into road_insp (insp_id, road_id, insp_date, condition) values (45,400,to_date('2019-05-01','YYYY-MM-DD'),.9);

insert into road_insp (insp_id, road_id, insp_date, condition) values (50,500,to_date('1994-05-01','YYYY-MM-DD'),.6);
insert into road_insp (insp_id, road_id, insp_date, condition) values (90,500,to_date('2006-05-01','YYYY-MM-DD'),.30);
insert into road_insp (insp_id, road_id, insp_date, condition) values (67,500,to_date('2010-05-01','YYYY-MM-DD'),.9);
insert into road_insp (insp_id, road_id, insp_date, condition) values (68,500,to_date('2014-05-01','YYYY-MM-DD'),.9);
insert into road_insp (insp_id, road_id, insp_date, condition) values (69,500,to_date('2017-05-01','YYYY-MM-DD'),.9);
insert into road_insp (insp_id, road_id, insp_date, condition) values (70,500,to_date('2020-05-01','YYYY-MM-DD'),.8);
insert into road_insp (insp_id, road_id, insp_date, condition) values (71,500,to_date('2023-05-01','YYYY-MM-DD'),.8);
insert into road_insp (insp_id, road_id, insp_date, condition) values (72,500,to_date('2026-05-01','YYYY-MM-DD'),.7);
insert into road_insp (insp_id, road_id, insp_date, condition) values (73,500,to_date('2029-05-01','YYYY-MM-DD'),.6);
insert into road_insp (insp_id, road_id, insp_date, condition) values (74,500,to_date('2032-05-01','YYYY-MM-DD'),.9);
insert into road_insp (insp_id, road_id, insp_date, condition) values (75,500,to_date('2035-05-01','YYYY-MM-DD'),.9);
commit;
select
    insp_id,
    road_id,
    to_char(insp_date,'YYYY-MM-DD') as insp_date_formatted,
    condition as condition
from
    road_insp
order by
    road_id,
    insp_date;

   INSP_ID    ROAD_ID INSP_DATE_FORMATTED  CONDITION
---------- ---------- ------------------- ----------
        40        400 1960-05-01                  .8
        41        400 2009-05-01                  .3
        42        400 2012-05-01                  .3
        43        400 2015-05-01                  .2  
        45        400 2019-05-01                  .9

        50        500 1994-05-01                  .6
        90        500 2006-05-01                  .3  
        67        500 2010-05-01                  .9
        68        500 2014-05-01                  .9
        69        500 2017-05-01                  .9
        70        500 2020-05-01                  .8
        71        500 2023-05-01                  .8
        72        500 2026-05-01                  .7
        73        500 2029-05-01                  .6 
        74        500 2032-05-01                  .9
        75        500 2035-05-01                  .9

---

When I union the tables together, they look like this:

select
    road_id,
    to_char(insp_date,'YYYY-MM-DD') as condition_date,
    condition as condition,
    'INSPECTION' as type
from
    road_insp
union all
select
    road_id,
    to_char(constr_date,'YYYY-MM-DD') as condition_date,
    reset_condition,
    'CONSTRUCTION' as type
from
    constr_events
order by
    road_id,
    condition_date

   ROAD_ID CONDITION_DATE  CONDITION TYPE        
---------- -------------- ---------- ------------
       400 1960-05-01             .8 INSPECTION  
       400 2009-05-01             .3 INSPECTION  
       400 2012-05-01             .3 INSPECTION  
       400 2015-05-01             .2 INSPECTION  
       400 2016-11-01              1 CONSTRUCTION
       400 2019-05-01             .9 INSPECTION  

       500 1994-05-01             .6 INSPECTION  
       500 2006-05-01             .3 INSPECTION  
       500 2009-11-01              1 CONSTRUCTION
       500 2010-05-01             .9 INSPECTION  
       500 2014-05-01             .9 INSPECTION  
       500 2017-05-01             .9 INSPECTION  
       500 2020-05-01             .8 INSPECTION  
       500 2023-05-01             .8 INSPECTION  
       500 2026-05-01             .7 INSPECTION  
       500 2029-05-01             .6 INSPECTION  
       500 2031-11-01              1 CONSTRUCTION
       500 2032-05-01             .9 INSPECTION  
       500 2035-05-01             .9 INSPECTION  

---

Question:

I would like to partition the data into groups. There would be a group for each construction event and the following inspections. Each lifecycle group would have an ID.

It would look like this:

+---------+----------------+-----------+--------------+-------------------+
| ROAD_ID | CONDITION_DATE | CONDITION |     TYPE     | LIFEYCYCLE_GROUP  | <<----
+---------+----------------+-----------+--------------+-------------------+
|     400 | 1960-05-01     |        .8 | INSPECTION   | 400-LIFECYCLE-1   |
|     400 | 2009-05-01     |        .3 | INSPECTION   | 400-LIFECYCLE-1   |
|     400 | 2012-05-01     |        .3 | INSPECTION   | 400-LIFECYCLE-1   |
|     400 | 2015-05-01     |        .2 | INSPECTION   | 400-LIFECYCLE-1   |
|         |                |           |              |                   |
|     400 | 2016-11-01     |         1 | CONSTRUCTION | 400-LIFECYCLE-2   |
|     400 | 2019-05-01     |        .9 | INSPECTION   | 400-LIFECYCLE-2   |
+---------+----------------+-----------+--------------+-------------------+
|     500 | 1994-05-01     |        .6 | INSPECTION   | 500-LIFECYCLE-1   |
|     500 | 2006-05-01     |        .3 | INSPECTION   | 500-LIFECYCLE-1   |
|         |                |           |              |                   |
|     500 | 2009-11-01     |         1 | CONSTRUCTION | 500-LIFECYCLE-2   |
|     500 | 2010-05-01     |        .9 | INSPECTION   | 500-LIFECYCLE-2   |
|     500 | 2014-05-01     |        .9 | INSPECTION   | 500-LIFECYCLE-2   |
|     500 | 2017-05-01     |        .9 | INSPECTION   | 500-LIFECYCLE-2   |
|     500 | 2020-05-01     |        .8 | INSPECTION   | 500-LIFECYCLE-2   |
|     500 | 2023-05-01     |        .8 | INSPECTION   | 500-LIFECYCLE-2   |
|     500 | 2026-05-01     |        .7 | INSPECTION   | 500-LIFECYCLE-2   |
|     500 | 2029-05-01     |        .6 | INSPECTION   | 500-LIFECYCLE-2   |
|         |                |           |              |                   |
|     500 | 2031-11-01     |         1 | CONSTRUCTION | 500-LIFECYCLE-3   |
|     500 | 2032-05-01     |        .9 | INSPECTION   | 500-LIFECYCLE-3   |
|     500 | 2035-05-01     |        .9 | INSPECTION   | 500-LIFECYCLE-3   |
+---------+----------------+-----------+--------------+-------------------+

There is a catch though. We don't always have a construction event for a road's initial construction. This is demonstrated in both of the roads in the sample data. The query would need to allow for this quirk by creating a group, even if there isn't an initial construction event.

How can I make this query?

Answer 1

Here's a rather clumsy solution (thank's for the ddl and sample data btw):

select road_id, condition_date, condition, type
     , to_char(road_id) 
        || '-LIFECYCLE-' 
        || to_char(dense_rank() over (partition by road_id order by grp)
        - case when type = 'CONSTRUCTION' then 1 else 0 end) as lifecycle_group
from (
    select road_id, condition_date, condition, type
         , (row_number() over (partition by road_id order by condition_date)
         - row_number() over (partition by road_id, type order by condition_date)) as grp
    from (
        select road_id, insp_date as condition_date
             , condition as condition, 'INSPECTION' as type
        from road_insp
        union all
        select road_id, constr_date as condition_date
             , reset_condition, 'CONSTRUCTION' as type
        from constr_events
    )
)
order by road_id, condition_date, grp;

The idea is to use different partitions for the row_number() functions (one with type, one without). If the difference between these changes it means that type has changed. We use this to create grp.

The case statement is used to compensate when type goes from CONSTRUCTION to INSPECTION.

This certainly can be improved in a number of ways, but will perhaps give you some ideas.

Answer 2

@ypercubeᵀᴹ's solution seemed to do the trick:

count(case when type='CONSTRUCTION' then 1 end) over (partition by road_id order by condition_date)