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https://issues.apache.org/jira/browse/SPARK-1647?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14110942#comment-14110942
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Giulio De Vecchi edited comment on SPARK-1647 at 8/27/14 10:33 AM:
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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, thus I would like 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.




was (Author: gadv):
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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