[GitHub] [calcite] chunweilei commented on a change in pull request #2017: [CALCITE-4018] Support trait propagation for EnumerableValues

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

chunweilei commented on a change in pull request #2017:
URL: https://github.com/apache/calcite/pull/2017#discussion_r437833608



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File path: core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableValues.java
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@@ -70,6 +74,32 @@ public static EnumerableValues create(RelOptCluster cluster,
     return new EnumerableValues(getCluster(), rowType, tuples, traitSet);
   }
 
+  @Override public RelNode passThrough(final RelTraitSet required) {
+    RelCollation collation = required.getCollation();
+    if (collation == null || collation.isDefault()) {
+      return null;
+    }
+    if (tuples.size() > 1) {
+      Ordering<List<RexLiteral>> ordering = null;
+      for (RelFieldCollation fc : collation.getFieldCollations()) {
+        Ordering<List<RexLiteral>> comparator = RelMdCollation.comparator(fc);
+        if (ordering == null) {
+          ordering = comparator;
+        } else {
+          ordering = ordering.compound(comparator);
+        }
+      }
+      if (!ordering.isOrdered(tuples)) {
+        return null;

Review comment:
       If the tuples are not sorted, we still have to add a sort on it. 




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