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From "An (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ACCUMULO-625) consider augmenting session state with "breadcrumbs"
Date Wed, 09 Jan 2013 13:36:12 GMT

    [ https://issues.apache.org/jira/browse/ACCUMULO-625?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13548514#comment-13548514
] 

An commented on ACCUMULO-625:
-----------------------------

Instead of tearing down the iterator at the end of every batch size is it possible to put
it in a suspended state so that when the iterator comes back up, all session state is restored?
It looks like if I use a scanner and enable Isolation the tear down process does not occur.
 This may be a coincident though.  This would work but BatchScanner do not have this functionality.
 Sending result through a WholeRowIterator is does not prevent the tear down process. Another
way is if we can consistently obtain when the tear down process occur for both Scanner and
BatchScanner.  For a Scanner one can just call getBatchSize() but again BatchScanners do not
have this functionality.


                
> consider augmenting session state with "breadcrumbs"
> ----------------------------------------------------
>
>                 Key: ACCUMULO-625
>                 URL: https://issues.apache.org/jira/browse/ACCUMULO-625
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: tserver
>            Reporter: Eric Newton
>            Assignee: Keith Turner
>
> Presently, the iterator stack can be created and destroyed at the whim of the tserver
and its buffering needs.  In complex iterations, lower-level iterators can make significant
progress which is not inherently obvious in any returned key.  When the iterator stack is
re-created to continue a query, the last key returned is used to {{seek()}} the iterators.
 Lower-level iterators must re-scan their data to move back to the old position.
> Consider a mechanism to save progress beyond the last key returned.
>   

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