Wsrtjtyk

I can use either SQL Server or Vertica as the DB and Tableau as the reporting tool. A solution in any of these mediums would be helpful.

DATA RESOURCES:
I have a table (userActivity) with 100 records and a structure of: User, StartDate, EndDate

NEED:
I am interested in preparing reports by day and month that show "total active days", meaning if User1 has a range of '20180101' to '20180331', they will contribute one day for each day in Jan, Feb and Mar OR 31, 28 and 31 days if aggregated by month.

GOAL:
I will ultimately be aggregating the total active days of all users as the output to achieve a single total for each day/month.

This report will span to perpetuity, so I would prefer solutions that don't hard code CASE/IF-THEN statements by day/month.

Thanks!

While recursive CTEs are a good candidate for this scenario, it can be handled with tableau alone. Assuming you have this data, here are the steps required to produce the view.

1. Create a reference sheet which has all the days expected. Even if you need to cover 25 years from 01/01/2018 to 01/01/2043, that is still less than 10k rows.

You need two columns with exact same date as Tableau does not allow multiple join conditions on same column.

2. Create an inner join between reference calendar and data using following criteria.
   



3. 
   

   Build the view

   
   
   

   

   
   

Use Vertica - it has the TIMESERIES clause - no recursion needed.

I would try the below - and check the intermediate results of the Common Table Expressions to see how it works..

WITH 

-- two test rows ....

input(uid,start_dt,end_dt) AS (

            SELECT 1,DATE '2018-01-01', DATE '2018-03-31'

  UNION ALL SELECT 2,DATE '2018-02-01', DATE '2018-04-01'

)

,

-- set the stage for Vertica's TIMESERIES clause

-- note: TIMESERIES relies on timestamps ...

limits(uid,lim_dt,qty) AS (

  SELECT

    uid

  , start_dt::TIMESTAMP

  , 1

  FROM input

  UNION ALL

  SELECT

    uid

  , end_dt::TIMESTAMP

  , 1

  FROM input

)

,

-- apply the Vertica TIMESERIES clause

counters AS (

  SELECT

    uid

  , act_dt

  , TS_FIRST_VALUE(qty) AS qty

  FROM limits

  TIMESERIES act_dt AS '1 DAY' OVER(PARTITION BY uid ORDER BY lim_dt)

)

SELECT

  uid

, MONTH(act_dt) AS activity_month

, SUM(qty)

FROM counters

GROUP BY 1,2;

-- out  uid | activity_month | sum 

-- out -----+----------------+-----

-- out    1 |              1 |  31

-- out    1 |              2 |  28

-- out    1 |              3 |  31

-- out    2 |              2 |  28

-- out    2 |              3 |  31

-- out    2 |              4 |   1

-- out (6 rows)

-- out 

-- out time: first fetch (6 rows): 120.515 ms. all rows formatted: 120.627 ms

Solution:

WITH base AS (

  SELECT

     User       AS u

    ,StartDate  AS s

    ,EndDate    AS e

    ,DATEDIFF(

      dd,

      StartDate,

      EndDate

      )+1       AS d

  FROM  userActivity

  ),

recurse AS (

  SELECT    u, s, e, d, x=(d-1)

    FROM    base

    UNION ALL

    SELECT  u, s, e, d, x-1 AS x

    FROM    recurse

    WHERE   x>0

  )

SELECT      u, DATEADD(dd, x, s) AS recordperday

FROM        recurse

ORDER BY    u, recordperday

--Extends SQL Server's recursion limit

OPTION (MAXRECURSION 500)