[GitHub] [spark] dongjoon-hyun commented on a diff in pull request #37197: [SPARK-39784][SQL] Put Literal values on the right side of the data source filter after translating Catalyst Expression to data source filter

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

dongjoon-hyun commented on code in PR #37197:
URL: https://github.com/apache/spark/pull/37197#discussion_r926261840


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sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/DataSourceV2Strategy.scala:
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@@ -502,11 +502,31 @@ private[sql] object DataSourceV2Strategy {
 
   private def translateLeafNodeFilterV2(predicate: Expression): Option[Predicate] = {
     predicate match {
-      case PushablePredicate(expr) => Some(expr)
+      case PushablePredicate(expr) =>
+        if (expr.children().length == 2) {
+          expr.children()(0) match {
+            case LiteralValue(_, _) =>
+              Some(new Predicate(flipComparisonFilterName(expr.name()),
+                Array(expr.children()(1), expr.children()(0))))
+            case _ => Some(expr)
+          }
+        } else {
+          Some(expr)
+        }
       case _ => None
     }
   }
 
+  private def flipComparisonFilterName(filterName: String): String = {
+    filterName match {
+      case ">" => "<"
+      case "<" => ">"
+      case ">=" => "<="
+      case "<=" => ">="
+      case _ => filterName

Review Comment:
   We don't need to flip `=`, do we? @zinking



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