[GitHub] [calcite] rubenada commented on a change in pull request #2550: [CALCITE-4809] mixed merge join result isn't incomplete

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

rubenada commented on a change in pull request #2550:
URL: https://github.com/apache/calcite/pull/2550#discussion_r718664412



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File path: linq4j/src/main/java/org/apache/calcite/linq4j/EnumerableDefaults.java
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@@ -4275,13 +4275,22 @@ private boolean advance() {
           // mergeJoin assumes inputs sorted in ascending order with nulls last,
           // if we reach a null key, we are done.
           if (leftKey == null || rightKey == null) {
-            if (joinType == JoinType.LEFT || (joinType == JoinType.ANTI && leftKey != null)) {
-              // all remaining items in left are results for left/anti join
-              remainingLeft = true;
-              return true;
+            if (rightKey == null || !(getLeftEnumerator() instanceof MergeJoinEnumerator

Review comment:
       This ad-hoc code should not be needed, as long as MergeJoin inputs respect the MergeJoin pre-requisite: they must be sorted by join keys in ascending order nulls last.
   I'd say the issue is not in this code, but on the module that creates the EnumerableMergeJoin, which perhaps does not introduce the appropriate Sort on its inputs.




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