**Requirement :**

Most of the popular reporting tools can handle cumulative sum or running total , but still there have been lot of posts in SCN about whether it is possible to do it in HANA itself. So, just wanted to see , if it can be easily done via Graphical Calculation view and it seems to be working .

Note: This might still be easier to do in Scripted View or Reporting Tool . Scripted Calculation View is deprecated now, instead use Table Function .

In Figure 1, our base data is in Column 1 and 2 and we want to add Colum 3 ( “C UM_SUM” ) to existing data set. .

*Figure 1 : Base data and result *

**Detail Steps :**

Figure 2 shows overall design of the calculation view. It is pretty simple one, isn’t it ?

*Figure 2 : Graphical Calculation View *

a) I have two projections ( ALL_DATA and ALL_DATA2 ) of the base data ( first two columns in Figure 1 )

b) Created one Calculated Column “DUMMY” on each projection and assigned it a value 1 . You can assign any other constant value .

c) In join node ( JOIN_1 ) ,(**inner**) joined these two data sets via ‘DUMMY” column . After joining output would be like below

*Figure 3: Output of Join node. *

If you notice, for every month now I shall have 12 records ( overall 12 X 12 = 144 ) . Where my Month matches with Month1 , that is my actual value for that month . And I need to sum all other values where Month >= Month1 . So, for above example, sum of 10, 20 and 30 would give me cumulative sum for Month 3.

To do this, I defined two calculated attributes , one to check if Month = Month1 and another to check If Month >= Month1 ( refer Figure 4 ) .

*Figure 4: Calculated Columns ( Attributes) on Join_1 node*

*d) * Now, I have two aggregation nodes. One with filter SAME_MONTH = “Y’ and another with GREATER_EQ_MONTH = ‘Y’ .

*Figure 5 : Aggregation node ( C UM_SUM ) –*

I took Month and Amount_1 and renamed Amount_1 to C UM_SUM .

*Figure 6 : Aggregation_2 *

Took Month and Amount with a Filter SAME_MONTH = ‘Y’ .

*e) *Lastly , we need to union these two aggregation nodes. Take Amount from one node and C UM_SUM from another node.

*Figure 7 : Union Node *

Result is in Figure 1 itself

**Note:** Model can be much more complex based on number of characteristics you take, in my case it was only Month . If you really want to go for this approach ( have enmity with script or coding ðŸ™‚ ) , do not use the base tables in JOIN_1 . Use this model after you aggregate data to a certain extent. Obviously , you would like to avoid a join **m X m** where m is a large number .

Equivalent SQL Code would be as simple as below . We can create a Calculation View ( Scripted) or Table Function using this SQL .

*a ) *

```
select a."Month" ,a."Amount" , ( select sum(b."Amount") from "<SCHEMA>"."RUN_SUM" b where a."Month" >= b."Month" ) as run_sum
from "<SCHEMA>"."RUN_SUM" a
order by a."Month"
```

*Or you can use Window function for better performance *

*b) *

```
select "Month" , "Amount" , Sum("Amount") over ( order by "Month") from "<SCHEMA>"."RUN_SUM"
order by "Month"
```

SQL in Section c running against a table with 1.3 **billion** records and I get the results in 40 **micro** seconds

c )

```
SELECT CALMONTH , ORDER_QUAN , SUM (ORDER_QUAN) OVER ( ORDER BY CALMONTH) AS SUM_VAL
FROM
( SELECT CALMONTH , SUM(ORDER_QUAN) AS "ORDER_QUAN" FROM "MY_TABLE"
WHERE CALMONTH BETWEEN '201401' AND '201603'
GROUP BY CALMONTH
)
```

*Please share your feedback and improvement suggestions *

Lars BreddemannNice work!

Although personally I think that you hit the nail on the head with this remark

It’s very likely also more efficient to simply use window functions in plain SQL or a table typed function (R.I.P. scripted calc views).

Anindya BosePost authorHi Lars

Thanks for the feedback. It is good to get feedback from experts like you .

Wanted to see if this can be done without a piece of code . I shall add equivalent SQL code to achieve the same .

Regards

Anindya

Anindya BosePost authorHi Lars

I see SQL Code and Graphical Calculation view both are creating Nested Loop Join . Does system understand what I am trying to do and creating Calc Scenario intelligently ?

Here is part of PlanViz . Please shed some light here .

Regards

Anindya

Lars BreddemannFrom what I can see you decided to implement the cumulative sum in SQL in a very similar fashion then what you did in the calc. view.

The scalar subquery gets rewritten into a join and that’s what you get in PlanViz.

A more efficient approach to ***. sum is to use window functions instead.

RAHUL KHANNAHi Folks,

I liked this approach for calculating the Cumulative sum which I am using in Hana but my concern is I am dealing with the millions of records whenever the Query is run it goes back to the 1 st record & start calculating the Sum based upon the Amount .

Is there any approach by which I could Â save my Sum as on today somewhere & then calculate the Sum from this point itself instead of going back to the 1st record

Hope that clears what I am trying to implement

Regards

Rahul

Andrea DavoliHi all,

someone try to add more dimension (with some cut-off dimension) to the model and can help me?

Andrea