Mingcong Han created SPARK-27411:
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Summary: DataSourceV2Strategy should not eliminate subquery
Key: SPARK-27411
URL: https://issues.apache.org/jira/browse/SPARK-27411
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 3.0.0
Reporter: Mingcong Han
Fix For: 3.0.0
In DataSourceV2Strategy, it seems we eliminate the subqueries by mistake after
normalizing filters. Here is an example:
We have an sql with a scalar subquery:
{code:scala}
val plan = spark.sql("select * from t2 where t2a > (select max(t1a) from t1)")
plan.explain(true)
{code}
And we get the log info of DataSourceV2Strategy:
{noformat}
Pushing operators to csv:examples/src/main/resources/t2.txt
Pushed Filters:
Post-Scan Filters: isnotnull(t2a#30)
Output: t2a#30, t2b#31
{noformat}
The `Post-Scan Filters` should contain the scalar subquery, but we eliminate it
by mistake.
{noformat}
== Parsed Logical Plan ==
'Project [*]
+- 'Filter ('t2a > scalar-subquery#56 [])
: +- 'Project [unresolvedalias('max('t1a), None)]
: +- 'UnresolvedRelation `t1`
+- 'UnresolvedRelation `t2`
== Analyzed Logical Plan ==
t2a: string, t2b: string
Project [t2a#30, t2b#31]
+- Filter (t2a#30 > scalar-subquery#56 [])
: +- Aggregate [max(t1a#13) AS max(t1a)#63]
: +- SubqueryAlias `t1`
: +- RelationV2[t1a#13, t1b#14] csv:examples/src/main/resources/t1.txt
+- SubqueryAlias `t2`
+- RelationV2[t2a#30, t2b#31] csv:examples/src/main/resources/t2.txt
== Optimized Logical Plan ==
Filter (isnotnull(t2a#30) && (t2a#30 > scalar-subquery#56 []))
: +- Aggregate [max(t1a#13) AS max(t1a)#63]
: +- Project [t1a#13]
: +- RelationV2[t1a#13, t1b#14] csv:examples/src/main/resources/t1.txt
+- RelationV2[t2a#30, t2b#31] csv:examples/src/main/resources/t2.txt
== Physical Plan ==
*(1) Project [t2a#30, t2b#31]
+- *(1) Filter isnotnull(t2a#30)
+- *(1) BatchScan[t2a#30, t2b#31] class
org.apache.spark.sql.execution.datasources.v2.csv.CSVScan
{noformat}
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