Hi, I'm currently familiarizing myself with the Flink Code and I have a question regarding operator chaining, maybe somebody could explain this to me?
The default Chaining Strategy is HEAD (meaning that the predecessor of the operator will not be chained, thus this operator may be the start of a chain but never in the middle or the end). This is overwritten by almost all operators that I looked at with ALWAYS, allowing the operator to be chained without limits. A counter example is StreamGroupedFold, which uses the default HEAD. My question is: Why does the StreamGroupedFold "interrupt" chaining and what is the general rule which operators may be chained limitless and which aren't. Also: Will all operators in a row that have ALWAYS chaining always end up in the same Chain/Task or may they be splitted when the Chain gets too long/complex? Thanks, Marius
