Clickhouse Tips #1: Calculating Aggregations After a Given Date
Imagine you have a table like
And you want to calculate, per day, the {% code-line %}sum(amount){% code-line-end %} of previous and following days.
For example, for the day {% code-line %}2020-01-05{% code-line-end %} you have to calculate {% code-line %}sumIf(amount, ts < '2020-01-05'){% code-line-end %} and {% code-line %}sumIf(amount, ts >= '2020-01-05'){% code-line-end %}
I think there are many ways to do it but this works:
Check out this snapshot for a step-by-step explanation of what’s going on here.
I think a way to exploit that values for each day don’t need to be calculated every time for each day using a nice function, arrayCumSum, plus some other array magic.
Check this out for a step-by-step explanation.
I feel there should be an easier way but that’s just a feeling.
%20(1).jpg)
