[jira] [Commented] (KAFKA-1275) fixes for quickstart documentation

["Sachin Goyal (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-1275?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14190556#comment-14190556 ] 

Sachin Goyal commented on KAFKA-1275:
-------------------------------------

[~joestein], [~jkreps], We are using Kafka 0.8.1.1 and we are thoroughly confused by the following statement:
{quote}
So the KeyedMessage val key:K is the primaryKey key (which is what is used to compact all older matching primary key messages leaving only the latest value (which for the use case is the only thing that would matter)) and the val partKey: Any is the partition key thrown away for deciding what partition to go on (same as < 0.8.1)
{quote}

The code we are using to send message to Kafka is:
{code}
String payload = ....;
String topic = ...;
String key = "" + System.currentTimeMillis();
KeyedMessage<String, String> data = new KeyedMessage<String, String>(topic, key, payload);
{code}

*Our concern is*:
Is it possible that when multiple threads are writing, some of them (with different payload) write with same partition key and because of that Kafka overwrites these messages (due to same partitionKey)?


Note that I am not talking about log compaction here.
I am talking from consumers' perspective.
*Is there a possibility that consumers can see missing payloads because their +key+ was same?*

If you can point me to the source code or the documentation, it would be much appreciated.

> fixes for quickstart documentation
> ----------------------------------
>
>                 Key: KAFKA-1275
>                 URL: https://issues.apache.org/jira/browse/KAFKA-1275
>             Project: Kafka
>          Issue Type: Bug
>          Components: website
>    Affects Versions: 0.8.1
>            Reporter: Evan Zacks
>            Assignee: Jay Kreps
>            Priority: Minor
>              Labels: documentation
>             Fix For: 0.8.1
>
>         Attachments: KAFKA-1275-quickstart-doc.patch
>
>
> The quickstart guide refers to commands that no longer exist in the master git branch per changes in KAFKA-554.
> If changes for the documentation to match 0.8.1 are already in development elsewhere, please feel free to discard this issue.



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