Great, thanks for the quick reply. Yes, I would use different buckets, that was a typo (copy/paste error). Of course I would use bucket1, bucket2, and so on.
I will def try it out. The flatMap is also very handy, when retrieving many docs from the same bucket. I do that in other cases, but here I want to use different buckets, and the merge operator will allow me to do that (with the .async() get calls).
Thanks again.