wangyum commented on a change in pull request #35214:
URL: https://github.com/apache/spark/pull/35214#discussion_r785770644
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
##########
@@ -766,18 +767,24 @@ object PushProjectionThroughUnion extends
Rule[LogicalPlan] with PredicateHelper
_.containsAllPatterns(UNION, PROJECT)) {
// Push down deterministic projection through UNION ALL
- case p @ Project(projectList, u: Union) =>
+ case Project(projectList, u: Union) if projectList.forall(_.deterministic)
=>
assert(u.children.nonEmpty)
- if (projectList.forall(_.deterministic)) {
- val newFirstChild = Project(projectList, u.children.head)
- val newOtherChildren = u.children.tail.map { child =>
- val rewrites = buildRewrites(u.children.head, child)
- Project(projectList.map(pushToRight(_, rewrites)), child)
- }
- u.copy(children = newFirstChild +: newOtherChildren)
- } else {
- p
+ val newFirstChild = Project(projectList, u.children.head)
+ val newOtherChildren = u.children.tail.map { child =>
+ val rewrites = buildRewrites(u.children.head, child)
+ Project(projectList.map(pushToRight(_, rewrites)), child)
+ }
+ u.copy(children = newFirstChild +: newOtherChildren)
+
+ // Push down deterministic projection through SQL UNION
+ case Project(projectList, Distinct(u: Union)) if
projectList.forall(_.deterministic) =>
Review comment:
Before this pr, there is a `Project` between `Distinct` and `Union`,
`CombineUnions` can not combine them, and later `ReplaceDistinctWithAggregate`
will replace `Distinct` with `Aggregate`.
```
Distinct
+- Union false, false
:- Project [cast(id#34 as decimal(22,5)) AS id#36]
: +- Distinct
: +- Union false, false
: :- Project [cast(id#32 as decimal(21,4)) AS id#34]
: : +- Distinct
: : +- Union false, false
: : :- Project [cast(id#30 as decimal(20,3)) AS id#32]
: : : +- Distinct
: : : +- Union false, false
: : : :- Project [cast(id#25 as decimal(19,2)) AS
id#30]
: : : : +- Relation default.t1[id#25] parquet
: : : +- Project [cast(id#26 as decimal(19,2)) AS
id#31]
: : : +- Relation default.t2[id#26] parquet
: : +- Project [cast(id#27 as decimal(20,3)) AS id#33]
: : +- Relation default.t3[id#27] parquet
: +- Project [cast(id#28 as decimal(21,4)) AS id#35]
: +- Relation default.t4[id#28] parquet
+- Project [cast(id#29 as decimal(22,5)) AS id#37]
+- Relation default.t5[id#29] parquet
```
After this pr, we first push project through union and then `CombineUnions`
can combine them.
```
=== Result of Batch PushProjectionThroughUnion ===
Distinct
Distinct
+- Union false, false
+- Union false, false
! :- Project [cast(id#34 as decimal(22,5)) AS id#36]
:- Distinct
! : +- Distinct
: +- Union false, false
! : +- Union false, false
: :- Distinct
! : :- Project [cast(id#32 as decimal(21,4)) AS id#34]
: : +- Union false, false
! : : +- Distinct
: : :- Distinct
! : : +- Union false, false
: : : +- Union false, false
! : : :- Project [cast(id#30 as decimal(20,3)) AS id#32]
: : : :- Project [cast(id#34 as decimal(22,5)) AS id#36]
! : : : +- Distinct
: : : : +- Project [cast(id#32 as decimal(21,4)) AS
id#34]
! : : : +- Union false, false
: : : : +- Project [cast(id#30 as decimal(20,3)) AS
id#32]
! : : : :- Project [cast(id#25 as decimal(19,2)) AS
id#30] : : : : +- Project [cast(id#25 as decimal(19,2))
AS id#30]
! : : : : +- Project [id#25]
: : : : +- Project [id#25]
! : : : : +- Relation default.t1[id#25] parquet
: : : : +- Relation default.t1[id#25] parquet
! : : : +- Project [cast(id#26 as decimal(19,2)) AS
id#31] : : : +- Project [cast(id#48 as decimal(22,5)) AS id#49]
! : : : +- Project [id#26]
: : : +- Project [cast(id#46 as decimal(21,4)) AS
id#48]
! : : : +- Relation default.t2[id#26] parquet
: : : +- Project [cast(id#31 as decimal(20,3)) AS
id#46]
! : : +- Project [cast(id#27 as decimal(20,3)) AS id#33]
: : : +- Project [cast(id#26 as decimal(19,2))
AS id#31]
! : : +- Project [id#27]
: : : +- Project [id#26]
! : : +- Relation default.t3[id#27] parquet
: : : +- Relation default.t2[id#26] parquet
! : +- Project [cast(id#28 as decimal(21,4)) AS id#35]
: : +- Project [cast(id#45 as decimal(22,5)) AS id#47]
! : +- Project [id#28]
: : +- Project [cast(id#33 as decimal(21,4)) AS id#45]
! : +- Relation default.t4[id#28] parquet
: : +- Project [cast(id#27 as decimal(20,3)) AS id#33]
! +- Project [cast(id#29 as decimal(22,5)) AS id#37]
: : +- Project [id#27]
! +- Project [id#29]
: : +- Relation default.t3[id#27] parquet
! +- Relation default.t5[id#29] parquet
: +- Project [cast(id#35 as decimal(22,5)) AS id#44]
!
: +- Project [cast(id#28 as decimal(21,4)) AS id#35]
!
: +- Project [id#28]
!
: +- Relation default.t4[id#28] parquet
!
+- Project [cast(id#29 as decimal(22,5)) AS id#37]
!
+- Project [id#29]
!
+- Relation default.t5[id#29] parquet
```
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