amaliujia commented on a change in pull request #2006:
URL: https://github.com/apache/calcite/pull/2006#discussion_r473193678
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File path:
core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableMergeJoin.java
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@@ -134,31 +138,82 @@ public static boolean isMergeJoinSupported(JoinRelType
joinType) {
final RelTraitSet required) {
// Required collation keys can be subset or superset of merge join keys.
RelCollation collation = required.getCollation();
+ int leftInputFieldCount = left.getRowType().getFieldCount();
+
List<Integer> reqKeys = RelCollations.ordinals(collation);
- ImmutableBitSet reqKeySet = ImmutableBitSet.of(reqKeys);
+ List<Integer> leftKeys = joinInfo.leftKeys.toIntegerList();
+ List<Integer> rightKeys =
+ joinInfo.rightKeys.incr(leftInputFieldCount).toIntegerList();
+ ImmutableBitSet reqKeySet = ImmutableBitSet.of(reqKeys);
ImmutableBitSet leftKeySet = ImmutableBitSet.of(joinInfo.leftKeys);
ImmutableBitSet rightKeySet = ImmutableBitSet.of(joinInfo.rightKeys)
- .shift(left.getRowType().getFieldCount());
+ .shift(leftInputFieldCount);
- // Only consider exact key match for now
if (reqKeySet.equals(leftKeySet)) {
+ // if sort keys equal to left join keys, we can pass through all
collations directly.
Mappings.TargetMapping mapping = buildMapping(true);
RelCollation rightCollation = collation.apply(mapping);
return Pair.of(
required, ImmutableList.of(required,
required.replace(rightCollation)));
+ } else if (containsOrderless(leftKeys, collation)) {
Review comment:
Got it. Will give a summary as java doc.
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