thinkharderdev commented on code in PR #16983:
URL: https://github.com/apache/datafusion/pull/16983#discussion_r2327178463
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datafusion/sqllogictest/test_files/aggregate.slt:
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@@ -7390,6 +7392,41 @@ query error Error during planning: ORDER BY and WITHIN
GROUP clauses cannot be u
SELECT array_agg(a_varchar order by a_varchar) WITHIN GROUP (ORDER BY
a_varchar)
FROM (VALUES ('a'), ('d'), ('c'), ('a')) t(a_varchar);
+statement ok
+SET datafusion.execution.target_partitions = 1;
+
+query TT
+EXPLAIN select * from (select 'id' as id union all select 'id' as id order by
id) group by grouping sets ((id), ());
+----
+logical_plan
+01)Projection: id
+02)--Aggregate: groupBy=[[GROUPING SETS ((id), ())]], aggr=[[]]
+03)----Union
+04)------Projection: Utf8("id") AS id
+05)--------EmptyRelation: rows=1
+06)------Projection: Utf8("id") AS id
+07)--------EmptyRelation: rows=1
+physical_plan
+01)ProjectionExec: expr=[id@0 as id]
+02)--AggregateExec: mode=FinalPartitioned, gby=[id@0 as id, __grouping_id@1 as
__grouping_id], aggr=[], ordering_mode=PartiallySorted([0])
+03)----CoalesceBatchesExec: target_batch_size=8192
+04)------RepartitionExec: partitioning=Hash([id@0, __grouping_id@1], 1),
input_partitions=2
Review Comment:
Sorry, been busy for past few days so just getting back to this. I think I
understand the underlying issue now since `id` is a const we infer it as a
singleton which is why we get the issue.
Still I'm concerned that we are solving this with a pretty blunt instrument.
Adding a repartition to ever aggregation with a grouping set can have a
non-trivial cost, especially in a distributed query.
Looking into it a bit more, it seems like in this case we infer
`SortProperties::Singleton` for the `id` expr in the final aggregation which I
think is incorrect.
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