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Posted to issues-all@impala.apache.org by "Tim Armstrong (Jira)" <ji...@apache.org> on 2020/04/01 23:22:00 UTC
[jira] [Resolved] (IMPALA-9317) Improve number of instances
estimate for scans in planner
[ https://issues.apache.org/jira/browse/IMPALA-9317?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Tim Armstrong resolved IMPALA-9317.
-----------------------------------
Fix Version/s: Impala 4.0
Resolution: Fixed
This was fixed as part of IMPALA-9156 in HdfsScanNode.java
> Improve number of instances estimate for scans in planner
> ---------------------------------------------------------
>
> Key: IMPALA-9317
> URL: https://issues.apache.org/jira/browse/IMPALA-9317
> Project: IMPALA
> Issue Type: Improvement
> Components: Frontend
> Reporter: Tim Armstrong
> Assignee: Tim Armstrong
> Priority: Major
> Labels: multithreading
> Fix For: Impala 4.0
>
>
> Currently the number of instances (used for various estimates) is calculated as estimated # hosts * mt_dop. This is suboptimal, because in many cases there isn't enough input data to allow creating that many instances per host.
> The per-host estimate for scans actually already handles this correctly by capping the hosts estimate at the number of input splits - we should use the same approach for number of instance estimates.
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