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https://issues.apache.org/jira/browse/TAJO-473?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jihoon Son resolved TAJO-473.
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Resolution: Won't Fix
LazyTaskScheduler is removed.
> Improve the fault tolerance of LazyTaskScheduler
> -------------------------------------------------
>
> Key: TAJO-473
> URL: https://issues.apache.org/jira/browse/TAJO-473
> Project: Tajo
> Issue Type: New Feature
> Components: query master
> Affects Versions: 0.2-incubating
> Reporter: Jihoon Son
>
> As discussed in TAJO-385 and https://reviews.apache.org/r/16455/, the
> LazyTaskScheduler has a problem when tasks are failed.
> When a failed task of multiple fragments is re-assigned to a node, the
> locality of fragments is extremely hard to preserved because it is nearly
> impossible that every fragments is stored at two or more common hosts.
> A simple and good solution is that creating multiple query unit attempts for
> each fragments when a failed task is reattempted. To implement this approach,
> we should maintain the information of the query processing attempt for each
> fragment, not for each query unit.
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