flink calculate median on stream

问题

I'm required to calculate median of many parameters received from a kafka stream for 15 min time window.

i couldn't find any built in function for that, but I have found a way using custom WindowFunction.

my questions are:

1. is it a difficult task for flink? the data can be very large.
2. if the data gets to giga bytes, will flink store everything in memory until the end of the time window? (one of the arguments of apply WindowFunction implementation is Iterable - a collection of all data which came during the time window )

thanks

来源：https://stackoverflow.com/questions/46451604/flink-calculate-median-on-stream