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Author: gengliangwang

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/DataSourceStrategy.scala

@@ -516,9 +516,9 @@ object DataSourceStrategy {
    * Tries to translate a Catalyst [[Expression]] into data source [[Filter]].
    *
    * @param predicate The input [[Expression]] to be translated as [[Filter]]
-   * @param translatedFilterToExpr Optional Mapping of all the leaf node filter expression to its
-   *                               translated [[Filter]]. The map is used for rebuilding Expression
-   *                               from [[Filter]]s.
+   * @param translatedFilterToExpr An optional map from leaf node filter expressions to its
+   *                               translated [[Filter]]. The map is used for rebuilding
+   *                               [[Expression]] from [[Filter]].
    * @return a `Some[Filter]` if the input [[Expression]] is convertible, otherwise a `None`.
    */
   protected[sql] def translateFilterWithMapping(

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/v2/DataSourceV2Strategy.scala

@@ -44,7 +44,10 @@ object DataSourceV2Strategy extends Strategy with PredicateHelper {
       filters: Seq[Expression]): (Seq[Expression], Seq[Expression]) = {
     scanBuilder match {
       case r: SupportsPushDownFilters =>
-        // A map from translated data source filters to original catalyst filter expressions.
+        // A map from translated data source leaf node filters to original catalyst filter
+        // expressions. For a `And`/`Or` predicate, it is possible that the predicate is partially
+        // pushed down. This map can used to construct a catalyst filter expression from the input
+        // filter, or a superset(partial push down filter) of the input filter.
         val translatedFilterToExpr = mutable.HashMap.empty[sources.Filter, Expression]
         val translatedFilters = mutable.ArrayBuffer.empty[sources.Filter]
         // Catalyst filter expression that can't be translated to data source filters.