dongjoon-hyun commented on a change in pull request #29942:
URL: https://github.com/apache/spark/pull/29942#discussion_r500610743
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/OptimizeJsonExprs.scala
##########
@@ -28,10 +28,45 @@ import org.apache.spark.sql.types.{ArrayType, StructType}
* The optimization includes:
* 1. JsonToStructs(StructsToJson(child)) => child.
* 2. Prune unnecessary columns from GetStructField/GetArrayStructFields +
JsonToStructs.
+ * 3. CreateNamedStruct(JsonToStructs(json).col1, JsonToStructs(json).col2,
...) =>
+ * CreateNamedStruct(JsonToStructs(json)) if JsonToStructs(json) is
shared among all
+ * fields of CreateNamedStruct.
*/
object OptimizeJsonExprs extends Rule[LogicalPlan] {
override def apply(plan: LogicalPlan): LogicalPlan = plan transform {
case p => p.transformExpressions {
+
+ case c: CreateNamedStruct
+ // If we create struct from various fields of the same
`JsonToStructs`.
+ if c.valExprs.forall { v =>
+ v.isInstanceOf[GetStructField] &&
+ v.asInstanceOf[GetStructField].child.isInstanceOf[JsonToStructs]
&&
+ v.children.head.semanticEquals(c.valExprs.head.children.head)
+ } =>
+ val jsonToStructs = c.valExprs.map(_.children.head)
+ val sameFieldName = c.names.zip(c.valExprs).forall {
+ case (name, valExpr: GetStructField) =>
+ name.toString == valExpr.childSchema(valExpr.ordinal).name
+ case _ => false
+ }
+
+ // Although `CreateNamedStruct` allows duplicated field names, e.g. "a
int, a int",
+ // `JsonToStructs` does not support parsing json with duplicated field
names.
+ val duplicateFields = c.names.map(_.toString).distinct.length !=
c.names.length
+
+ // If we create struct from various fields of the same `JsonToStructs`
and we don't
+ // alias field names and there is not duplicated field in the struct.
Review comment:
`not` -> `no`?
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