How to use the “Combine new with old results” option
How the “Combine new with old results” advanced option works in Dataslayer?
You can find this option in the Dataslayer extension, below the OPTIONS tab.

It works by automatically accumulating the information of your old data with the new one when you modify, refresh or schedule your queries. It is very useful since old data is no longer overwritten, it is accumulated.
A temporal dimension is always needed when you want to use this option
Limitations
You cannot combine the "combine new with old results option" with the "exclude header row" option.
When the combine option is on, we look through the dimension and metric headers to see if that value has already been inserted before to replace it, insert it at the end of the table, or skip it. If you exclude the header row, the table does not return the metrics or dimensions names, so we only have the values of the metrics and since they are equal to previous values, they are being replaced instead of being inserted at the end. So the results may come out with discrepancies.
For example, if you select "Month" as a dimension and you have both options selected, since the header has been omitted and the table does not return the "Month" field, we only have the value of the metrics and the new value it's going to replace the old one, instead of being accumulated.
The solution to this is to select only one of the two options, but not both together.
Click here to know more about the other advanced options Dataslayer has.
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Updated on: 29/11/2022
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