AngersZhuuuu commented on a change in pull request #32201:
URL: https://github.com/apache/spark/pull/32201#discussion_r618090727
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File path: docs/sql-ref-syntax-qry-select-groupby.md
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@@ -113,7 +117,10 @@ aggregate_name ( [ DISTINCT ] expression [ , ... ] ) [
FILTER ( WHERE boolean_ex
(warehouse, location),
(warehouse, size),
(warehouse))`.
-
+
+ `GROUP BY GROUPING SETS(GROUPING SETS(warehouse, product), GROUPING
SETS(location, size))` is equivalent to
+ `GROUP BY GROUPING SETS((warehouse, product), (location, size))`.
Review comment:
> interesting, so nested grouping set is just syntax sugar for
specifying a grouping set?
It seems yes, the benefit is we can write CUBE/ROLLUP in GROUPING SETS.
since `GROUP BY GROUPING SETS((A, B), (A), (), (A, C))` can write as
`GROUPING BY(ROLLUP(A, B), (A, C))`
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