uranusjr commented on code in PR #69075:
URL: https://github.com/apache/airflow/pull/69075#discussion_r3488532028
##########
task-sdk/src/airflow/sdk/definitions/xcom_arg.py:
##########
@@ -354,8 +354,11 @@ def resolve(self, context: Mapping[str, Any]) -> Any:
ti_count=ti_count,
session=None, # Not used in SDK implementation
)
- # None means "no filtering needed" -> use NOTSET to pull all
values
- map_indexes = NOTSET if computed is None else computed
+ if computed is None:
+ # Aggregate the mapped task group as a list, even for a
single expansion (#69036) or all-None values (#48005)
+ # Materialise eagerly (one slice request) so a task
returning the value unchanged can still serialize it
+ return LazyXComSequence(xcom_arg=self, ti=ti)[:]
+ map_indexes = computed
Review Comment:
Hmm, this has the potential to kill performance is the map size is large. I
wonder if it would be appropriate to return the lazy sequence directly, and
handle it on XCom serialization _if_ it’s actually returned instead.
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