Using sort after aggregator

[ray.wurlod]

Yes, but its absence will cause the framework to insert a tsort operator in any case, unless you use input link sorting on the Join stage. Because the Join stage requires sorted input, DataStage makes sure it can "see" something - directly on the input link - that guarantees sorted data.

Better, I feel, would be to leave the Sort stage in place, but to set its Sort Mode property to "Don't Sort, Previously Sorted".
Presence of the Sort stage comforts the Join stage into not inserting any different form of tsort operator.