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Posted to issues@hive.apache.org by "Zoltan Haindrich (JIRA)" <ji...@apache.org> on 2018/08/31 15:12:00 UTC
[jira] [Commented] (HIVE-20491) Fix mapjoin size estimations for
Fast implementation
[ https://issues.apache.org/jira/browse/HIVE-20491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16598822#comment-16598822 ]
Zoltan Haindrich commented on HIVE-20491:
-----------------------------------------
I've looked into this a little bit more...and there seems to be 2 core fast implementations and 1 optimized.
There is a Fast implementation for long keys; and another which for string/other keys; in case of these complex keys the optimized implementation handles memory better.
> Fix mapjoin size estimations for Fast implementation
> ----------------------------------------------------
>
> Key: HIVE-20491
> URL: https://issues.apache.org/jira/browse/HIVE-20491
> Project: Hive
> Issue Type: Improvement
> Components: Statistics
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
>
> HIVE-19824 have fixed the estimations; but it calculated for the "optimized" impl; the "fast" one has a little bit bigger footprint.
> It also seems like fast is a bit overestimated at runtime...that should be also taken care of.
> | numkeys | implementation | compiler estimation | runtime estimation | runtime measurement | ce / rm | re / rm |
> | 25M | FAST | 1168435456 | 2189433712 | 1513584984 | .77 | 1.44 |
> | 25M | OPTIMIZED | 1168435456 | 1191203764 | 1168439664 | 100% | 1.01 |
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