flink evictors and eager window functions

Question

i am confused about the relation between flink evictors and eagerly evaluated window functions such as AggregateFunction and ReduceFunction,

From the flink doc: (https://ci.apache.org/projects/flink/flink-docs-stable/dev/stream/operators/windows.html#evictors)

The evictor has the ability to remove elements from a window after the trigger fires and before and/or after the window function is applied

sounds like the evictor is NOT eager, then what's the behavior of using an evictor with an AggregateFunction? Is there a moment in time when all the elements are assigned in the window in RAM?

Thanks

Answer 1

Attention Specifying an evictor prevents any pre-aggregation, as all the elements of a window have to be passed to the evictor before applying the computation.

i missed this line of flink .