[GitHub] [spark] maropu commented on a change in pull request #28805: [SPARK-28169][SQL] Convert scan predicate condition to CNF

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

maropu commented on a change in pull request #28805:
URL: https://github.com/apache/spark/pull/28805#discussion_r448053925



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File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala
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@@ -249,8 +251,36 @@ trait PredicateHelper extends Logging {
     resultStack.top
   }
 
-  private def groupExpressionsByQualifier(expressions: Seq[Expression]): Seq[Expression] = {
-    expressions.groupBy(_.references.map(_.qualifier)).map(_._2.reduceLeft(And)).toSeq
+  /**
+   * Convert an expression to conjunctive normal form when pushing predicates through Join,
+   * when expand predicates, we can group by the qualifier avoiding generate unnecessary
+   * expression to control the length of final result since there are multiple tables.
+   * @param condition condition need to be convert

Review comment:
       nit: convert -> converted




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