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@yhuang-db yhuang-db commented Oct 6, 2025

What changes were proposed in this pull request?

This PR proposes to add doCanonicalize function for DataSourceV2ScanRelation. The implementation is similar to the one in BatchScanExec, as well as the the one in LogicalRelation.

Why are the changes needed?

Query optimization rules such as MergeScalarSubqueries check if two plans are identical by comparing their canonicalized form. For DSv2, for physical plan, the canonicalization goes down in the child hierarchy to the BatchScanExec, which has a doCanonicalize function; for logical plan, the canonicalization goes down to the DataSourceV2ScanRelation, which, however, does not have a doCanonicalize function. As a result, two logical plans who are semantically identical are not identified.

Moreover, for reference, DSv1 LogicalRelation also has doCanonicalize().

Does this PR introduce any user-facing change?

No

How was this patch tested?

A new unit test is added to show that MergeScalarSubqueries is working for DataSourceV2ScanRelation.

For a query

select (select max(i) from df) as max_i, (select min(i) from df) as min_i

Before introducing the canonicalization, the plan is

== Parsed Logical Plan ==
'Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- 'Project [unresolvedalias('max('i))]
:  :  +- 'UnresolvedRelation [df], [], false
:  +- 'Project [unresolvedalias('min('i))]
:     +- 'UnresolvedRelation [df], [], false
+- OneRowRelation

== Analyzed Logical Plan ==
max_i: int, min_i: int
Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- Aggregate [max(i#0) AS max(i)#7]
:  :  +- SubqueryAlias df
:  :     +- View (`df`, [i#0, j#1])
:  :        +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
:  +- Aggregate [min(i#10) AS min(i)#9]
:     +- SubqueryAlias df
:        +- View (`df`, [i#10, j#11])
:           +- RelationV2[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
+- OneRowRelation

== Optimized Logical Plan ==
Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- Aggregate [max(i#0) AS max(i)#7]
:  :  +- Project [i#0]
:  :     +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
:  +- Aggregate [min(i#10) AS min(i)#9]
:     +- Project [i#10]
:        +- RelationV2[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
+- OneRowRelation

== Physical Plan ==
AdaptiveSparkPlan isFinalPlan=true
+- == Final Plan ==
   ResultQueryStage 0
   +- *(1) Project [Subquery subquery#2, [id=#32] AS max_i#3, Subquery subquery#4, [id=#33] AS min_i#5]
      :  :- Subquery subquery#2, [id=#32]
      :  :  +- AdaptiveSparkPlan isFinalPlan=true
            +- == Final Plan ==
               ResultQueryStage 1
               +- *(2) HashAggregate(keys=[], functions=[max(i#0)], output=[max(i)#7])
                  +- ShuffleQueryStage 0
                     +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=58]
                        +- *(1) HashAggregate(keys=[], functions=[partial_max(i#0)], output=[max#14])
                           +- *(1) Project [i#0]
                              +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
            +- == Initial Plan ==
               HashAggregate(keys=[], functions=[max(i#0)], output=[max(i)#7])
               +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=19]
                  +- HashAggregate(keys=[], functions=[partial_max(i#0)], output=[max#14])
                     +- Project [i#0]
                        +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
      :  +- Subquery subquery#4, [id=#33]
      :     +- AdaptiveSparkPlan isFinalPlan=true
            +- == Final Plan ==
               ResultQueryStage 1
               +- *(2) HashAggregate(keys=[], functions=[min(i#10)], output=[min(i)#9])
                  +- ShuffleQueryStage 0
                     +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=63]
                        +- *(1) HashAggregate(keys=[], functions=[partial_min(i#10)], output=[min#15])
                           +- *(1) Project [i#10]
                              +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
            +- == Initial Plan ==
               HashAggregate(keys=[], functions=[min(i#10)], output=[min(i)#9])
               +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=30]
                  +- HashAggregate(keys=[], functions=[partial_min(i#10)], output=[min#15])
                     +- Project [i#10]
                        +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
      +- *(1) Scan OneRowRelation[]
+- == Initial Plan ==
   Project [Subquery subquery#2, [id=#32] AS max_i#3, Subquery subquery#4, [id=#33] AS min_i#5]
   :  :- Subquery subquery#2, [id=#32]
   :  :  +- AdaptiveSparkPlan isFinalPlan=true
         +- == Final Plan ==
            ResultQueryStage 1
            +- *(2) HashAggregate(keys=[], functions=[max(i#0)], output=[max(i)#7])
               +- ShuffleQueryStage 0
                  +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=58]
                     +- *(1) HashAggregate(keys=[], functions=[partial_max(i#0)], output=[max#14])
                        +- *(1) Project [i#0]
                           +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
         +- == Initial Plan ==
            HashAggregate(keys=[], functions=[max(i#0)], output=[max(i)#7])
            +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=19]
               +- HashAggregate(keys=[], functions=[partial_max(i#0)], output=[max#14])
                  +- Project [i#0]
                     +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
   :  +- Subquery subquery#4, [id=#33]
   :     +- AdaptiveSparkPlan isFinalPlan=true
         +- == Final Plan ==
            ResultQueryStage 1
            +- *(2) HashAggregate(keys=[], functions=[min(i#10)], output=[min(i)#9])
               +- ShuffleQueryStage 0
                  +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=63]
                     +- *(1) HashAggregate(keys=[], functions=[partial_min(i#10)], output=[min#15])
                        +- *(1) Project [i#10]
                           +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
         +- == Initial Plan ==
            HashAggregate(keys=[], functions=[min(i#10)], output=[min(i)#9])
            +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=30]
               +- HashAggregate(keys=[], functions=[partial_min(i#10)], output=[min#15])
                  +- Project [i#10]
                     +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
   +- Scan OneRowRelation[]

After introducing the canonicalization, the plan is as following, where you can see ReusedSubquery

== Parsed Logical Plan ==
'Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- 'Project [unresolvedalias('max('i))]
:  :  +- 'UnresolvedRelation [df], [], false
:  +- 'Project [unresolvedalias('min('i))]
:     +- 'UnresolvedRelation [df], [], false
+- OneRowRelation

== Analyzed Logical Plan ==
max_i: int, min_i: int
Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- Aggregate [max(i#0) AS max(i)#7]
:  :  +- SubqueryAlias df
:  :     +- View (`df`, [i#0, j#1])
:  :        +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
:  +- Aggregate [min(i#10) AS min(i)#9]
:     +- SubqueryAlias df
:        +- View (`df`, [i#10, j#11])
:           +- RelationV2[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
+- OneRowRelation

== Optimized Logical Plan ==
Project [scalar-subquery#2 [].max(i) AS max_i#3, scalar-subquery#4 [].min(i) AS min_i#5]
:  :- Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
:  :  +- Aggregate [max(i#0) AS max(i)#7, min(i#0) AS min(i)#9]
:  :     +- Project [i#0]
:  :        +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
:  +- Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
:     +- Aggregate [max(i#0) AS max(i)#7, min(i#0) AS min(i)#9]
:        +- Project [i#0]
:           +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
+- OneRowRelation

== Physical Plan ==
AdaptiveSparkPlan isFinalPlan=true
+- == Final Plan ==
   ResultQueryStage 0
   +- *(1) Project [Subquery subquery#2, [id=#40].max(i) AS max_i#3, ReusedSubquery Subquery subquery#2, [id=#40].min(i) AS min_i#5]
      :  :- Subquery subquery#2, [id=#40]
      :  :  +- AdaptiveSparkPlan isFinalPlan=true
            +- == Final Plan ==
               ResultQueryStage 1
               +- *(2) Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
                  +- *(2) HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
                     +- ShuffleQueryStage 0
                        +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=71]
                           +- *(1) HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
                              +- *(1) Project [i#0]
                                 +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
            +- == Initial Plan ==
               Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
               +- HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
                  +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=22]
                     +- HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
                        +- Project [i#0]
                           +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
      :  +- ReusedSubquery Subquery subquery#2, [id=#40]
      +- *(1) Scan OneRowRelation[]
+- == Initial Plan ==
   Project [Subquery subquery#2, [id=#40].max(i) AS max_i#3, Subquery subquery#4, [id=#41].min(i) AS min_i#5]
   :  :- Subquery subquery#2, [id=#40]
   :  :  +- AdaptiveSparkPlan isFinalPlan=true
         +- == Final Plan ==
            ResultQueryStage 1
            +- *(2) Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
               +- *(2) HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
                  +- ShuffleQueryStage 0
                     +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=71]
                        +- *(1) HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
                           +- *(1) Project [i#0]
                              +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
         +- == Initial Plan ==
            Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
            +- HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
               +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=22]
                  +- HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
                     +- Project [i#0]
                        +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
   :  +- Subquery subquery#4, [id=#41]
   :     +- AdaptiveSparkPlan isFinalPlan=false
   :        +- Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
   :           +- HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
   :              +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=37]
   :                 +- HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
   :                    +- Project [i#0]
   :                       +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
   +- Scan OneRowRelation[]

Was this patch authored or co-authored using generative AI tooling?

No

@github-actions github-actions bot added the SQL label Oct 6, 2025
@peter-toth
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@yhuang-db , can you please check the test failures? Some of them seems related to your change.

@yhuang-db yhuang-db changed the title [SPARK-53809][SQL]Add canonicalization for DSv2 scan [SPARK-53809][SQL]Add canonicalization for DataSourceV2ScanRelation Oct 10, 2025
@yhuang-db yhuang-db marked this pull request as ready for review October 22, 2025 23:01
Array(RangeInputPartition(0, 5), RangeInputPartition(5, 10))
}

override def equals(obj: Any): Boolean = {
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equals needs to be implemented by scan itself.

Connector would have it own scan implementation, hence DataSourceV2ScanRelation cannot canonicalize the scan object by itself.

@yhuang-db
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Hi @peter-toth, I've added more description to justify the change and added tests to test the change. All checks have passed now. Please feel free to comment. Thanks!

// Check that the aggregate contains both max(i) and min(i)
val aggExprs = agg.aggregateExpressions

val hasMax = aggExprs.exists { expr =>
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Maybe it is better to extract the logic to the helper function or even better to just collect the aggregate functions to a collection and test it against the expected set.

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LGTM, just a minor suggestion.

Thanks for the fix!

@peter-toth peter-toth changed the title [SPARK-53809][SQL]Add canonicalization for DataSourceV2ScanRelation [SPARK-53809][SQL] Add canonicalization for DataSourceV2ScanRelation Nov 1, 2025
@peter-toth peter-toth closed this in 0732e44 Nov 1, 2025
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Thank you @yhuang-db for the fix.

Merged to master (4.1.0).

huangxiaopingRD pushed a commit to huangxiaopingRD/spark that referenced this pull request Nov 25, 2025
### What changes were proposed in this pull request?

This PR proposes to add `doCanonicalize` function for DataSourceV2ScanRelation. The implementation is similar to [the one in BatchScanExec](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/BatchScanExec.scala#L150), as well as the [the one in LogicalRelation](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/LogicalRelation.scala#L52).

### Why are the changes needed?

Query optimization rules such as MergeScalarSubqueries check if two plans are identical by [comparing their canonicalized form](https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/MergeScalarSubqueries.scala#L219). For DSv2, for physical plan, the canonicalization goes down in the child hierarchy to the BatchScanExec, which [has a doCanonicalize function](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/BatchScanExec.scala#L150); for logical plan, the canonicalization goes down to the DataSourceV2ScanRelation, which, however, does not have a doCanonicalize function. As a result, two logical plans who are semantically identical are not identified.

Moreover, for reference, [DSv1 LogicalRelation](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/LogicalRelation.scala#L52) also has `doCanonicalize()`.

### Does this PR introduce _any_ user-facing change?

No

### How was this patch tested?

A new unit test is added to show that `MergeScalarSubqueries` is working for DataSourceV2ScanRelation.

For a query
```sql
select (select max(i) from df) as max_i, (select min(i) from df) as min_i
```

Before introducing the canonicalization, the plan is
```
== Parsed Logical Plan ==
'Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- 'Project [unresolvedalias('max('i))]
:  :  +- 'UnresolvedRelation [df], [], false
:  +- 'Project [unresolvedalias('min('i))]
:     +- 'UnresolvedRelation [df], [], false
+- OneRowRelation

== Analyzed Logical Plan ==
max_i: int, min_i: int
Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- Aggregate [max(i#0) AS max(i)#7]
:  :  +- SubqueryAlias df
:  :     +- View (`df`, [i#0, j#1])
:  :        +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
:  +- Aggregate [min(i#10) AS min(i)#9]
:     +- SubqueryAlias df
:        +- View (`df`, [i#10, j#11])
:           +- RelationV2[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
+- OneRowRelation

== Optimized Logical Plan ==
Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- Aggregate [max(i#0) AS max(i)#7]
:  :  +- Project [i#0]
:  :     +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
:  +- Aggregate [min(i#10) AS min(i)#9]
:     +- Project [i#10]
:        +- RelationV2[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
+- OneRowRelation

== Physical Plan ==
AdaptiveSparkPlan isFinalPlan=true
+- == Final Plan ==
   ResultQueryStage 0
   +- *(1) Project [Subquery subquery#2, [id=#32] AS max_i#3, Subquery subquery#4, [id=#33] AS min_i#5]
      :  :- Subquery subquery#2, [id=#32]
      :  :  +- AdaptiveSparkPlan isFinalPlan=true
            +- == Final Plan ==
               ResultQueryStage 1
               +- *(2) HashAggregate(keys=[], functions=[max(i#0)], output=[max(i)#7])
                  +- ShuffleQueryStage 0
                     +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=58]
                        +- *(1) HashAggregate(keys=[], functions=[partial_max(i#0)], output=[max#14])
                           +- *(1) Project [i#0]
                              +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
            +- == Initial Plan ==
               HashAggregate(keys=[], functions=[max(i#0)], output=[max(i)#7])
               +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=19]
                  +- HashAggregate(keys=[], functions=[partial_max(i#0)], output=[max#14])
                     +- Project [i#0]
                        +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
      :  +- Subquery subquery#4, [id=#33]
      :     +- AdaptiveSparkPlan isFinalPlan=true
            +- == Final Plan ==
               ResultQueryStage 1
               +- *(2) HashAggregate(keys=[], functions=[min(i#10)], output=[min(i)#9])
                  +- ShuffleQueryStage 0
                     +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=63]
                        +- *(1) HashAggregate(keys=[], functions=[partial_min(i#10)], output=[min#15])
                           +- *(1) Project [i#10]
                              +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
            +- == Initial Plan ==
               HashAggregate(keys=[], functions=[min(i#10)], output=[min(i)#9])
               +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=30]
                  +- HashAggregate(keys=[], functions=[partial_min(i#10)], output=[min#15])
                     +- Project [i#10]
                        +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
      +- *(1) Scan OneRowRelation[]
+- == Initial Plan ==
   Project [Subquery subquery#2, [id=#32] AS max_i#3, Subquery subquery#4, [id=#33] AS min_i#5]
   :  :- Subquery subquery#2, [id=#32]
   :  :  +- AdaptiveSparkPlan isFinalPlan=true
         +- == Final Plan ==
            ResultQueryStage 1
            +- *(2) HashAggregate(keys=[], functions=[max(i#0)], output=[max(i)#7])
               +- ShuffleQueryStage 0
                  +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=58]
                     +- *(1) HashAggregate(keys=[], functions=[partial_max(i#0)], output=[max#14])
                        +- *(1) Project [i#0]
                           +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
         +- == Initial Plan ==
            HashAggregate(keys=[], functions=[max(i#0)], output=[max(i)#7])
            +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=19]
               +- HashAggregate(keys=[], functions=[partial_max(i#0)], output=[max#14])
                  +- Project [i#0]
                     +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
   :  +- Subquery subquery#4, [id=#33]
   :     +- AdaptiveSparkPlan isFinalPlan=true
         +- == Final Plan ==
            ResultQueryStage 1
            +- *(2) HashAggregate(keys=[], functions=[min(i#10)], output=[min(i)#9])
               +- ShuffleQueryStage 0
                  +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=63]
                     +- *(1) HashAggregate(keys=[], functions=[partial_min(i#10)], output=[min#15])
                        +- *(1) Project [i#10]
                           +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
         +- == Initial Plan ==
            HashAggregate(keys=[], functions=[min(i#10)], output=[min(i)#9])
            +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=30]
               +- HashAggregate(keys=[], functions=[partial_min(i#10)], output=[min#15])
                  +- Project [i#10]
                     +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
   +- Scan OneRowRelation[]
```

After introducing the canonicalization, the plan is as following, where you can see **ReusedSubquery**
```
== Parsed Logical Plan ==
'Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- 'Project [unresolvedalias('max('i))]
:  :  +- 'UnresolvedRelation [df], [], false
:  +- 'Project [unresolvedalias('min('i))]
:     +- 'UnresolvedRelation [df], [], false
+- OneRowRelation

== Analyzed Logical Plan ==
max_i: int, min_i: int
Project [scalar-subquery#2 [] AS max_i#3, scalar-subquery#4 [] AS min_i#5]
:  :- Aggregate [max(i#0) AS max(i)#7]
:  :  +- SubqueryAlias df
:  :     +- View (`df`, [i#0, j#1])
:  :        +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
:  +- Aggregate [min(i#10) AS min(i)#9]
:     +- SubqueryAlias df
:        +- View (`df`, [i#10, j#11])
:           +- RelationV2[i#10, j#11] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
+- OneRowRelation

== Optimized Logical Plan ==
Project [scalar-subquery#2 [].max(i) AS max_i#3, scalar-subquery#4 [].min(i) AS min_i#5]
:  :- Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
:  :  +- Aggregate [max(i#0) AS max(i)#7, min(i#0) AS min(i)#9]
:  :     +- Project [i#0]
:  :        +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
:  +- Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
:     +- Aggregate [max(i#0) AS max(i)#7, min(i#0) AS min(i)#9]
:        +- Project [i#0]
:           +- RelationV2[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5
+- OneRowRelation

== Physical Plan ==
AdaptiveSparkPlan isFinalPlan=true
+- == Final Plan ==
   ResultQueryStage 0
   +- *(1) Project [Subquery subquery#2, [id=#40].max(i) AS max_i#3, ReusedSubquery Subquery subquery#2, [id=#40].min(i) AS min_i#5]
      :  :- Subquery subquery#2, [id=#40]
      :  :  +- AdaptiveSparkPlan isFinalPlan=true
            +- == Final Plan ==
               ResultQueryStage 1
               +- *(2) Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
                  +- *(2) HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
                     +- ShuffleQueryStage 0
                        +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=71]
                           +- *(1) HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
                              +- *(1) Project [i#0]
                                 +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
            +- == Initial Plan ==
               Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
               +- HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
                  +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=22]
                     +- HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
                        +- Project [i#0]
                           +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
      :  +- ReusedSubquery Subquery subquery#2, [id=#40]
      +- *(1) Scan OneRowRelation[]
+- == Initial Plan ==
   Project [Subquery subquery#2, [id=#40].max(i) AS max_i#3, Subquery subquery#4, [id=#41].min(i) AS min_i#5]
   :  :- Subquery subquery#2, [id=#40]
   :  :  +- AdaptiveSparkPlan isFinalPlan=true
         +- == Final Plan ==
            ResultQueryStage 1
            +- *(2) Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
               +- *(2) HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
                  +- ShuffleQueryStage 0
                     +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=71]
                        +- *(1) HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
                           +- *(1) Project [i#0]
                              +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
         +- == Initial Plan ==
            Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
            +- HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
               +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=22]
                  +- HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
                     +- Project [i#0]
                        +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
   :  +- Subquery subquery#4, [id=#41]
   :     +- AdaptiveSparkPlan isFinalPlan=false
   :        +- Project [named_struct(max(i), max(i)#7, min(i), min(i)#9) AS mergedValue#14]
   :           +- HashAggregate(keys=[], functions=[max(i#0), min(i#0)], output=[max(i)#7, min(i)#9])
   :              +- Exchange SinglePartition, ENSURE_REQUIREMENTS, [plan_id=37]
   :                 +- HashAggregate(keys=[], functions=[partial_max(i#0), partial_min(i#0)], output=[max#16, min#17])
   :                    +- Project [i#0]
   :                       +- BatchScan class org.apache.spark.sql.connector.SimpleDataSourceV2$$anon$5[i#0, j#1] class org.apache.spark.sql.connector.SimpleDataSourceV2$MyScanBuilder RuntimeFilters: []
   +- Scan OneRowRelation[]
```

### Was this patch authored or co-authored using generative AI tooling?

No

Closes apache#52529 from yhuang-db/scan-canonicalization.

Authored-by: yhuang-db <[email protected]>
Signed-off-by: Peter Toth <[email protected]>
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