amaliujia commented on a change in pull request #2006:
URL: https://github.com/apache/calcite/pull/2006#discussion_r438534299
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File path:
core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableMergeJoin.java
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@@ -101,28 +103,55 @@ public static boolean isMergeJoinSupported(JoinRelType
joinType) {
// Required collation keys can be subset or superset of merge join keys.
RelCollation collation = required.getTrait(RelCollationTraitDef.INSTANCE);
List<Integer> reqKeys = RelCollations.ordinals(collation);
- ImmutableBitSet reqKeySet = ImmutableBitSet.of(reqKeys);
+ // need to copy reqKeys because it is not sortable.
+ reqKeys = new ArrayList<>(reqKeys);
+ List<Integer> leftKeys = immutableIntListToList(joinInfo.leftKeys, 0);
+ List<Integer> rightKeys = immutableIntListToList(joinInfo.rightKeys,
+ left.getRowType().getFieldCount());
+ List<Integer> rightKeysNotShifted =
immutableIntListToList(joinInfo.rightKeys, 0);
+ ImmutableBitSet reqKeySet = ImmutableBitSet.of(reqKeys);
ImmutableBitSet leftKeySet = ImmutableBitSet.of(joinInfo.leftKeys);
ImmutableBitSet rightKeySet = ImmutableBitSet.of(joinInfo.rightKeys)
.shift(left.getRowType().getFieldCount());
Map<Integer, Integer> keyMap = new HashMap<>();
- final int keyCount = leftKeySet.cardinality();
+ final int keyCount = leftKeys.size();
for (int i = 0; i < keyCount; i++) {
keyMap.put(joinInfo.leftKeys.get(i), joinInfo.rightKeys.get(i));
}
Mappings.TargetMapping mapping = Mappings.target(keyMap,
left.getRowType().getFieldCount(),
right.getRowType().getFieldCount());
- // 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.
RelCollation rightCollation = RexUtil.apply(mapping, collation);
return Pair.of(
required, ImmutableList.of(required,
required.replace(rightCollation)));
+ } else if (isSubset(reqKeys, leftKeys)) {
+ // if sort keys are subset of left join keys, we can extend collations
to make sure all join
+ // keys are sorted.
+ collation = extendCollation(collation, leftKeys);
+ RelCollation rightCollation = RexUtil.apply(mapping, collation);
+ return Pair.of(
+ required, ImmutableList.of(required.replace(collation),
+ required.replace(rightCollation)));
+ } else if (isPrefixOrderingNotRequired(leftKeys, reqKeys)
Review comment:
`containsOrderless` only consider if one is another's subset, for
example:
[1, 2, 3] is [2, 3, 4, 1]'s subset
[3, 2, 1] is [2, 1, 3, 4] 's subset
The prefix requirement is, still use examples above, but apply sublist:
[2,3,4,1] -> [2,3,4], then containsOrderless([1,2,3]) = false.
[2,1,3,4] ->[2,1,3], then containsOrderless([3,2,1]) = true.
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