rubenada commented on a change in pull request #2006:
URL: https://github.com/apache/calcite/pull/2006#discussion_r473006265
##########
File path:
core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableMergeJoin.java
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@@ -222,6 +277,30 @@ public static boolean isMergeJoinSupported(JoinRelType
joinType) {
return mapping;
}
+ private RelCollation extendCollation(RelCollation collation, List<Integer>
keys) {
+ List<RelFieldCollation> fieldsForNewCollation = new
ArrayList<>(keys.size());
+ fieldsForNewCollation.addAll(collation.getFieldCollations());
+ Set<Integer> keySet = new HashSet<>(keys);
+ for (RelFieldCollation rf : collation.getFieldCollations()) {
+ keySet.remove(rf.getFieldIndex());
+ }
+ for (Integer i : keySet) {
+ fieldsForNewCollation.add(new RelFieldCollation(i));
+ }
+ return RelCollations.of(fieldsForNewCollation);
+ }
+
+ private RelCollation removeCollationFieldsNotOnJoinKey(
Review comment:
I also think the method name is counter-intuitive. It is actually not
removing anything, it just builds a new collation based on a "source"
collation, considering only the fields which are part of the joinKeys. I would
propose as name e.g. `reduceCollation`, `intersect`, or something like that..
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