> you can easily express any operations you want That's true in that the table api itself is built on top of the datastream api. But to run the example you'd h

> you can easily express any operations you want That's true in that the table api itself is built on top of the datastream api. But to run the example you'd have to implement your own joins and retraction-aware aggregates and then we'd be testing the consistency properties of that implementation, not of the datastream api itself, and we might as well test a mature implementation like the table api instead.