Github user jihoonson commented on a diff in the pull request:
https://github.com/apache/tajo/pull/1009#discussion_r61831252
--- Diff:
tajo-core/src/main/java/org/apache/tajo/engine/function/window/Rank.java ---
@@ -48,7 +48,8 @@ public Rank() {
public static boolean checkIfDistinctValue(RankContext context, Tuple
params) {
for (int i = 0; i < context.latest.length; i++) {
- if (!context.latest[i].equalsTo(params.asDatum(i)).isTrue()) {
+ if ((context.latest[i].isNotNull() || params.asDatum(i).isNotNull())
--- End diff --
Because, in rank(), null values are regarded as the same unlike our other
implementations. Please refer to
https://en.wikipedia.org/wiki/Three-valued_logic.
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