[GitHub] [kafka] mjsax commented on a change in pull request #9186: KAFKA-10277: Allow null keys with non-null mappedKey in KStreamKGlobalTable join

[GitBox <gi...@apache.org>]

mjsax commented on a change in pull request #9186:
URL: https://github.com/apache/kafka/pull/9186#discussion_r485095735



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File path: streams/src/main/java/org/apache/kafka/streams/kstream/internals/KStreamKTableJoinProcessor.java
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@@ -58,22 +58,23 @@ public void init(final ProcessorContext context) {
 
     @Override
     public void process(final K1 key, final V1 value) {
-        // we do join iff keys are equal, thus, if key is null we cannot join and just ignore the record
-        // If {@code keyMapper} returns {@code null} it implies there is no match,
+        // We allow null keys unless {@code keyMapper} returns {@code null} and we ignore it as invalid.

Review comment:
       I guess we don't care about the original `key` any longer and only consider if `keyMapper` returns `null` or not?




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