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Posted to issues@spark.apache.org by "Giulio De Vecchi (JIRA)" <ji...@apache.org> on 2014/08/26 18:55:58 UTC
[jira] [Commented] (SPARK-1647) Prevent data loss when Streaming
driver goes down
[ https://issues.apache.org/jira/browse/SPARK-1647?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14110942#comment-14110942 ]
Giulio De Vecchi commented on SPARK-1647:
-----------------------------------------
Not sure if this make sense, but maybe would be nice to have a kind of "flag" available within the code that tells me if I'm running in a "normal" situation or during a recovery.
To better explain this, let's consider the following scenario:
I am processing data, let's say from a Kafka streaming, and I am updating a database based on the computations. During the recovery I don't want to update again the database (for many reasons, let's just assume that) but I want my system to be in the same status as before, so I would be able to "know" if my code is running for the first time or during a recovery so I can avoid to update the database again.
More generally I want to know this in case I'm interacting with external entities.
> Prevent data loss when Streaming driver goes down
> -------------------------------------------------
>
> Key: SPARK-1647
> URL: https://issues.apache.org/jira/browse/SPARK-1647
> Project: Spark
> Issue Type: Bug
> Components: Streaming
> Reporter: Hari Shreedharan
> Assignee: Hari Shreedharan
>
> Currently when the driver goes down, any uncheckpointed data is lost from within spark. If the system from which messages are pulled can replay messages, the data may be available - but for some systems, like Flume this is not the case.
> Also, all windowing information is lost for windowing functions.
> We must persist raw data somehow, and be able to replay this data if required. We also must persist windowing information with the data itself.
> This will likely require quite a bit of work to complete and probably will have to be split into several sub-jiras.
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