francis0407 commented on a change in pull request #23783: [SPARK-26854][SQL]
Support ANY/SOME subquery
URL: https://github.com/apache/spark/pull/23783#discussion_r257452132
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala
##########
@@ -1148,6 +1165,12 @@ class AstBuilder(conf: SQLConf) extends
SqlBaseBaseVisitor[AnyRef] with Logging
EqualNullSafe(e, expression(ctx.right))
case SqlBaseParser.DISTINCT =>
Not(EqualNullSafe(e, expression(ctx.right)))
+ case SqlBaseParser.ANY | SqlBaseParser.SOME =>
+ invertIfNotDefined(AnySubquery(
+ getValueExpressions(e),
+ getComparisonOperator(
+
ctx.comparisonOperator.getChild(0).asInstanceOf[TerminalNode].getSymbol.getType),
+ ListQuery(plan(ctx.query))))
Review comment:
Hi, I found another problem during revision.
If we use `AnySubquery(cmp: BinaryComparison)`, `left` inside the `cmp` is
an `Expression` instead of `Seq[Expression]`, which can not be analyzed by the
rule `ResolveReferences`(since it uses `mapProductIterator`).
Therefore, I have to define it as
```scala
case class AnySubquery(values: Seq[Expression], cmp: BinaryComparison,
query: ListQuery)
```
and define another apply function as
```scala
object AnySubqury {
def apply(cmp: BinaryComparison): AnySubquery = ...
}
```
As a result, this becomes more and more unnatural.
I am wondering if it is necessary to restrict the type of `comparison` as
`BinaryComparison`. If it is not, then we won't need `NotEqualTo()` any more
and we can define `AnySubquery` as
```scala
case class AnySubquery(values: Seq[Expression], comparison: (Expression,
Expression) => Expression, query: ListQuery)
```
There is no need to rewrite `comparison` either.
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