hsyuan commented on a change in pull request #1995:
URL: https://github.com/apache/calcite/pull/1995#discussion_r432953832
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File path:
core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableHashJoin.java
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@@ -100,6 +106,53 @@ public static EnumerableHashJoin create(
condition, variablesSet, joinType);
}
+ @Override public Pair<RelTraitSet, List<RelTraitSet>> passThroughTraits(
+ final RelTraitSet required) {
+ RelCollation collation = required.getCollation();
+ if (collation == null || collation == RelCollations.EMPTY) {
+ return null;
+ }
+
+ List<Integer> requiredKeys = RelCollations.ordinals(collation);
+ ImmutableBitSet requiredKeySet = ImmutableBitSet.of(requiredKeys);
+
+ ImmutableBitSet leftKeySet = ImmutableBitSet.of(joinInfo.leftKeys);
+ ImmutableBitSet rightKeySet = ImmutableBitSet.of(joinInfo.rightKeys)
+ .shift(left.getRowType().getFieldCount());
+
+ // HashJoin traits passdown shall only consider left/right outer join.
+ // It is because for a hash-based implementation, only non-hashed side can
+ // preserve ordering, thus only for left/right outer join, we are sure
which
+ // side is non-hashed side (the outer child).
+ if (joinType == JoinRelType.LEFT) {
Review comment:
On the other hand, it shows exactly that trait propagation should only
be done on physical operators, because it is physical implementation dependent.
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