rubenada commented on code in PR #5393:
URL: https://github.com/apache/calcite/pull/5393#discussion_r4495805717
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linq4j/src/main/java/org/apache/calcite/linq4j/EnumerableDefaults.java:
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@@ -5424,6 +5424,36 @@ private static class BothValuesAreNullException extends
RuntimeException {
}
}
+ /** Variant of {@link #compareNullsLastForMergeJoin(Comparable, Comparable,
Comparator)}
+ * for values that are not {@link Comparable}, such as ROW and ARRAY values.
+ * Throws {@link BothValuesAreNullException} if both values are null. */
+ public static <T> int compareObjectsNullsLastForMergeJoin(@Nullable T v0,
+ @Nullable T v1, Comparator<? super T> comparator) {
+ return compareObjectsNullsLastForMergeJoin(v0, v1, comparator, null);
+ }
+
+ /** Compares merge join keys, optionally rejecting equal keys containing
NULL fields.
+ * Checks fields only after comparing keys, so unequal keys retain their
sort order. */
+ public static <T> int compareObjectsNullsLastForMergeJoin(@Nullable T v0,
+ @Nullable T v1, Comparator<? super T> comparator,
+ @Nullable Predicate1<? super T> containsNull) {
+ if (v0 == null && v1 == null) {
+ throw new BothValuesAreNullException();
+ }
+ if (v0 == null) {
+ return 1;
+ }
+ if (v1 == null) {
+ return -1;
+ }
+ final int c = comparator.compare(v0, v1);
+ if (c == 0 && containsNull != null
+ && (containsNull.apply(v0) || containsNull.apply(v1))) {
Review Comment:
Technically, if `c == 0` then it should be enough to check
`containsNull.apply(v0)` , so we could skip the `containsNull.apply(v1)`; we
could keep it, since it's harmless. In any case, a comment here is probably
worth it, to clarify that "this is a row type with a NULL inside, so we need to
throw the same signal as two null keys to advance without matching"
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