Troubleshooting (Actionable Insights)
Issues with Null Values When Joining Series
Issue 1: Cannot calculate Measure – null value in Join Series
I create a Datamart Watcher and configure Series 1 and Series 2 using three fields in Group By: Customer ID, Customer Group and Customer Class (this field contains null value). The Measure is ∑Quantity.
I add Join Series using the three Dimensions above with Measure being s2∑Quantity/s1∑Quantity.
I click Apply Settings and check the tables and I can see that there is a value for customer ID CG-0001 in Series 1 and 2 but it returns null value in Join Series.
Issue 2: Detection Rule is applied to the null value
I continue with Watcher configured above. In the Join Series there are 154 rows.
In Detection Rules I applied a condition Compare Quantity is greater than -1.
I finish the Watcher setup and submit it for approval to create Actions.
I open the Action item. In the Detected Insight table there are 153 rows – the row with the null value has been removed.
Recommended Solution
Avoid selecting fields containing rows with null values as dimensions in the Join Series definition. A database Join will not join two rows that have null value in the same field because null != null.
Null values also cannot be compared with other values, so a filter like Quantity > -1
will always omit a row with a null value.