At the moment, backfills can’t be stopped, once started. This is due to data integrity issues, according to the support.

However, there are some cases, where a backfill might be cancelled without issues for data integrity.

E.g. if I added metric A to a table, started a backfill and immediately noticed I need to include metric B as well. In this case I would anyhow start a new backfill and data integrity is no issue. However, at the moment I need to wait for the backfill with metric A to be completed which is time consuming for me and somehow expensive for you.