peter-toth commented on pull request #32298:
URL: https://github.com/apache/spark/pull/32298#issuecomment-1076546385
@sigmod, how about doing this kind of transformation?
```
SELECT
(SELECT avg(a) FROM t GROUP BY b),
(SELECT sum(b) FROM t GROUP BY b)
FROM T
```
=>
```
WITH cte AS (SELECT named_struct(a, avg(a), b, sum(b)) mergedValue FROM t
GROUP BY b)
SELECT (SELECT mergedValue FROM cte).a, (SELECT mergedValue FROM cte).b
FROM T
```
and adding a flag to `cte` `CTERelationDef` that it hosts a scalar query +
changing `WithCTEStrategy` a bit to avoid extra shuffles in those cases as
`ReuseExchangeAndSubquery` can insert `ReusedSubqueryExec` nodes (no need to
insert `ReusedExchangeExec`).
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