Forum Discussion
Issues in Incremental refresh
Hi, Anonymous
Please refer to the following solutions to see if they are helpful to you.
Problem: Refresh fails because of duplicate values
Cause: Post dates have changed
With a refresh operation, only data that has changed at the data source is refreshed in the dataset. As the data is divided by a date, it’s recommended post (transaction) dates are not changed.
If a date is changed accidentally, then two issues can occur: Users notice some totals changed in the historical data (that is not supposed to happen), or during a refresh an error is returned indicating a unique value is not in fact unique. For the latter, this can happen when the table with incremental refresh configured is used in a 1:N relationship with another table as the 1 side and should have unique values. When the data is changed (for a specific ID), that ID then appears in another partition and the engine will detect the value is not unique.
Solution: Refresh specific partitions
Where there is a business need to change some past data from the dates, a possible solution is to use SSMS to refresh all partitions from the point where the change is located up to the current refresh partition, thus keeping the 1 side of the relationship unique.
Please refer to the following documents.
https://docs.microsoft.com/power-bi/connect-data/incremental-refresh-troubleshoot
Best Regards,
Community Support Team _Charlotte
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
We're in the same boat. Lots of data changing over time (like an opportunity status, or an order amount). The only way we have found that is halfway acceptable is to have a separate process that judges which partitions need refreshing, and then initiates these refreshes via XMLA. If this sounds like the OLAP cube refreshes of yore - yep, that's what it basically is.
To add insult to injury - if you use standard incremental refresh partition management then you are bound by regular calendar periods. We use a fiscal calendar that often results in more partitions (or parts thereof) being refreshed than strictly needed.
There is no magic to any of this, it is all tedious work.
https://docs.microsoft.com/en-us/power-bi/connect-data/incremental-refresh-xmla Advanced incremental refresh and meta data changes
https://docs.microsoft.com/en-us/power-bi/admin/service-premium-incremental-refresh#override-incremental-refresh-behavior special features for incremental refresh
https://learn.microsoft.com/en-us/power-bi/connect-data/incremental-refresh-troubleshoot Troubleshoot incremental refresh
Late reply but for those that come here after a search:
I believe it needs an immutable datetime column, not necessarily that the whole row needs to be immutable. If you have an immutable column like a creationdate log column you can use that together with detect data changes on a modifieddate log column. If you set your partitions at the month level for example it will scan each month for a change in last modifieddate and then refresh the entire partition.