elitongadotti opened a new issue, #33329:
URL: https://github.com/apache/beam/issues/33329
### What happened?
Setup:
- Python SDK, version 2.60.0
- Dataflow Runner
- Streaming Job
What happened?
Take a streaming job that reads from a PubSub subscription, do some
transformations and sink it back to PubSub Topic.
The message has a lot of duplicate "rows", I need to expose the primary key
for an element and `GroupByKey()` to be able to fetch the latest one. Once I
expose `pk` and group by it, the step downstream might have keys with no
values.
**If I remove the** `early=trigger.AfterProcessingTime(some_time)` **it did
work as expected (keys and values are emitted together)**.
It does not make sense to emit to the downstream steps only keys but not
values. Both are part of the same output tuple and they cannot be emitted
separately.
Here's part of the code:
(
to_sync
| "AddTimestamp" >> beam.ParDo(AddTimestamp())
| "Window" >> beam.WindowInto(
windowfn=window.FixedWindows(60),
trigger=trigger.AfterWatermark(early=trigger.AfterProcessingTime(30)),
accumulation_mode=trigger.AccumulationMode.DISCARDING
)
| "GroupAndFetchLatest" >> GroupAndFetchLatest()
...
)
class GroupAndFetchLatest(beam.PTransform):
"""Expose record PK, group by it and fetch the latest record
(timestamp)"""
def expand(self, pcoll):
return (
pcoll
| "ExposeKey" >> beam.Map(lambda x: (x["mykey"], x))
| "Group" >> beam.GroupByKey()
| "GetLatest" >> beam.ParDo(GetLatest())
)
class GetLatest(beam.DoFn):
def process(self, grouped):
key, values = grouped
if values: # Here, I had to add this "if" to avoid keys without
values.
latest = max(values, key=lambda o: o["__ts__"])
yield MyObject(
PK=key,
row=latest
)
### Issue Priority
Priority: 2 (default / most bugs should be filed as P2)
### Issue Components
- [X] Component: Python SDK
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- [X] Component: Google Cloud Dataflow Runner
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