[CH]Pushdown extra projection before `expand`

apache / incubator-gluten

Gluten is a middle layer responsible for offloading JVM-based SQL engines' execution to native engines.

https://gluten.apache.org/

Apache License 2.0

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Closed lgbo-ustc closed 6 days ago

lgbo-ustc commented 1 week ago

For following query


select x, y, count(if(a > 0, b, c)) as n from t
group by x, y with cube

It will add an extra projection after expand for pre-calculating if(a>0,b, c).

For performance, we should push down the projection before expand

lgbo-ustc commented 1 week ago

before pushdown

after pushdown