[GitHub] [iceberg] aokolnychyi commented on a change in pull request #2189: Spark: Optimize insert only case in MERGE

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

aokolnychyi commented on a change in pull request #2189:
URL: https://github.com/apache/iceberg/pull/2189#discussion_r567561536



##########
File path: spark3-extensions/src/main/scala/org/apache/spark/sql/catalyst/optimizer/RewriteMergeInto.scala
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@@ -158,6 +144,43 @@ case class RewriteMergeInto(spark: SparkSession) extends Rule[LogicalPlan] with
     }
   }
 
+  // when there are no matched actions, use a left anti join to remove any matching rows and rewrite to use
+  // append instead of replace. only unmatched source rows are passed to the merge and actions are all inserts.
+  private def buildInsertOnlyMergePlan(
+      targetTableScan: LogicalPlan,
+      targetTableOutput: Seq[AttributeReference],
+      source: LogicalPlan,
+      cond: Expression,
+      notMatchedActions: Seq[MergeAction]): LogicalPlan = {
+
+    notMatchedActions match {
+      case Seq(insertAction: InsertAction) =>
+        val filteredSource = insertAction.condition match {

Review comment:
       In case of a filter in `NOT MATCHED` clause, we can execute it before the join.




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