rubenada commented on code in PR #5393:
URL: https://github.com/apache/calcite/pull/5393#discussion_r4492056064
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core/src/test/java/org/apache/calcite/test/SqlFunctionsTest.java:
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@@ -1004,6 +1004,21 @@ private void checkCeil(int x, int y, int result) {
assertThat(Utilities.compare(empty, empty), is(0));
}
+ /** Composite null keys compare equally for sorting, but must not match in a
merge join. */
+ @Test void testCompareCompositeNullKeys() {
+ final Object key = new Object[]{1, null};
+ assertThat(Utilities.compareCompositeNullsFirst(null, null), is(0));
+ assertThat(Utilities.compareCompositeNullsLast(null, null), is(0));
+ assertThat(Utilities.compareCompositeNullsLastForMergeJoin(null, key),
is(1));
+ assertThat(Utilities.compareCompositeNullsLastForMergeJoin(key, null),
is(-1));
+ assertThat(Utilities.compareCompositeNullsLastForMergeJoin(key, new
Object[]{1, null}), is(0));
Review Comment:
Is this intended? IIUC merge join will match ROW(1, NULL) with ROW(1, NULL),
while SQL says ROW(1, NULL) = ROW(1, NULL) is UNKNOWN, is this not a bug on the
Join algorithm? Is this consistent with Calcite's HashJoin, or PostgreSQL join
behavior?
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