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https://issues.apache.org/jira/browse/IMPALA-7928?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Work on IMPALA-7928 started by Joe McDonnell.
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> Investigate consistent placement of remote scan ranges
> ------------------------------------------------------
>
> Key: IMPALA-7928
> URL: https://issues.apache.org/jira/browse/IMPALA-7928
> Project: IMPALA
> Issue Type: Bug
> Components: Backend
> Affects Versions: Impala 3.2.0
> Reporter: Joe McDonnell
> Assignee: Joe McDonnell
> Priority: Critical
>
> With the file handle cache, it is useful for repeated scans of the same file
> to go to the same node, as that node will already have a file handle cached.
> When scheduling remote ranges, the scheduler introduces randomness that can
> spread reads across all of the nodes. Repeated executions of queries on the
> same set of files will not schedule the remote reads on the same nodes. This
> causes a large amount of duplication across file handle caches on different
> nodes. This reduces the efficiency of the cache significantly.
> It may be useful for the scheduler to introduce some determinism in
> scheduling remote reads to take advantage of the file handle cache. This is a
> variation on the well-known tradeoff between skew and locality.
>
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