StackOverflowError for simple map (not to incubator mailing list)

(Sorry, first one sent to incubator maling list which probably doesn't come here) Hi, I have been stuck at this for a week. I have a relatively simple dataframe like this: +-+-++---+ | item| item_id| target| start

StackOverflowError for simple map

Hi, I have been stuck at this for a week. I have a relatively simple dataframe like this: +-+-++---+ | item| item_id| target| start| +-+-++---+ |sensor123|sensor1