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https://issues.apache.org/jira/browse/KAFKA-4750?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16097368#comment-16097368
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Matthias J. Sax edited comment on KAFKA-4750 at 7/22/17 3:41 PM:
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IMHO, we can also improve the code by not calling the serializer in the first 
place if we get a {{put(key, null)}}. Thus, we can insure that {{rawValue}} 
will be {{null}} even if the serializer might not return {{null}}.


was (Author: mjsax):
IMHO, we can also improve the code by not calling the serializer in the first 
place if we get a `put(key, null)`. Thus, we can insure that `rawValue` will be 
`null` even if the serializer might not return `null`.

> KeyValueIterator returns null values
> ------------------------------------
>
>                 Key: KAFKA-4750
>                 URL: https://issues.apache.org/jira/browse/KAFKA-4750
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>    Affects Versions: 0.10.1.1, 0.10.2.1, 0.11.0.0
>            Reporter: Michal Borowiecki
>            Assignee: Evgeny Veretennikov
>              Labels: newbie
>         Attachments: DeleteTest.java
>
>
> The API for ReadOnlyKeyValueStore.range method promises the returned iterator 
> will not return null values. However, after upgrading from 0.10.0.0 to 
> 0.10.1.1 we found null values are returned causing NPEs on our side.
> I found this happens after removing entries from the store and I found 
> resemblance to SAMZA-94 defect. The problem seems to be as it was there, when 
> deleting entries and having a serializer that does not return null when null 
> is passed in, the state store doesn't actually delete that key/value pair but 
> the iterator will return null value for that key.
> When I modified our serilizer to return null when null is passed in, the 
> problem went away. However, I believe this should be fixed in kafka streams, 
> perhaps with a similar approach as SAMZA-94.



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