Incremental refresh - changes in old data

Hi Anonymous ,

Based on my understand, if we set store rows for where "extraction date" is in the last 5 years and refresh rows  where "extraction date" is in the last 30 days, then the refresh start at 2020-03-14 06:00:00 AM, it will refresh the rows where "extraction date" is between 2020-02-13 06:00:00 AM and 2020-03-14 06:00:00 AM, and all the rows where "extraction date" is between 2015-03-14 06:00:00 AM and between 2020-02-13 06:00:00 AM will keep as the same, and then the rows where "extraction date" is earlier than the 2020-02-13 06:00:00 AM will be dropped. 

So In your scenario, if the data in 2018 changed to earlier than 2020-02-13 06:00:00 AM,those rows will not change and keep as old if the refresh range is only set as 30 days. If it change to 2020-03-12 08:00:00, Based on our test, it will keep the old row and add a new rows: 

Please refer to following document about more information of Incremental Refresh:

https://docs.microsoft.com/en-us/power-bi/service-premium-incremental-refresh#configure-incremental-refresh

https://docs.microsoft.com/en-us/power-bi/service-dataflows-incremental-refresh#incremental-refresh-implementation-details

Best regards,