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https://issues.apache.org/jira/browse/FLINK-26799?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17511550#comment-17511550
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Feifan Wang commented on FLINK-26799:
-------------------------------------

Hi [~roman] , I'm not mean seek on the underlying stream before wrapping. We 
should always seek on the wrapper stream as long as the offset not equal to 0. 
I think the code should be like below :

 
{code:java}
if (offset != 0) {
    LOG.debug("seek from {} to {}", stream.getPos(), offset);
    input.skipBytesToRead((int) offset);
} {code}
 

> StateChangeFormat#read not seek to offset correctly
> ---------------------------------------------------
>
>                 Key: FLINK-26799
>                 URL: https://issues.apache.org/jira/browse/FLINK-26799
>             Project: Flink
>          Issue Type: Bug
>          Components: Runtime / State Backends
>            Reporter: Feifan Wang
>            Priority: Major
>
> StateChangeFormat#read must seek to offset before read, current implement as 
> follows :
>  
> {code:java}
> FSDataInputStream stream = handle.openInputStream();
> DataInputViewStreamWrapper input = wrap(stream);
> if (stream.getPos() != offset) {
>     LOG.debug("seek from {} to {}", stream.getPos(), offset);
>     input.skipBytesToRead((int) offset);
> }{code}
> But the if condition is incorrect, stream.getPos() return the position of 
> underlying stream which is different from position of input.
> By the way, because of wrapped by BufferedInputStream, position of underlying 
> stream always at n*bufferSize or the end of file. 
> Actually, input is aways at position 0 at beginning, so I think we can seek 
> to the offset directly.
>  



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