[GitHub] [spark] viirya commented on a change in pull request #29942: [SPARK-33007][SQL] Simplify named_struct + get struct field + from_json expression chain

[GitBox <gi...@apache.org>]

viirya commented on a change in pull request #29942:
URL: https://github.com/apache/spark/pull/29942#discussion_r499355316



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File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/OptimizeJsonExprs.scala
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@@ -28,10 +28,36 @@ 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  struct(from_json.col1, from_json.col2, from_json.col3...) => struct(from_json)
  */
 object OptimizeJsonExprs extends Rule[LogicalPlan] {
   override def apply(plan: LogicalPlan): LogicalPlan = plan transform {
     case p => p.transformExpressions {
+
+      case c: CreateNamedStruct
+        if c.valExprs.forall(v => v.isInstanceOf[GetStructField] &&
+          v.asInstanceOf[GetStructField].child.isInstanceOf[JsonToStructs]) =>
+        val jsonToStructs = c.valExprs.map(_.children(0))
+        val semanticEqual = jsonToStructs.tail.forall(jsonToStructs.head.semanticEquals(_))

Review comment:
       We can but L39 condition will look ugly.




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