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https://issues.apache.org/jira/browse/HIVE-22962?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17053800#comment-17053800
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Jesus Camacho Rodriguez commented on HIVE-22962:
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[~gopalv], [~rajesh.balamohan], [~vgarg], could you take a look? Thanks
https://github.com/apache/hive/pull/943
Preliminary results are quite promising (posted above). I also implemented the
warm up for the cache when HS2 comes up. The reason why I kept
{{RelFieldTrimmer}} around instead of merging {{RelFieldTrimmer}} and
{{HiveRelFieldTrimmer}} is that I do not know when I will be able to merge
these changes into Calcite, hence it will make easier to bring new version of
field trimmer whenever Calcite is upgraded (basically {{RelFieldTrimmer}} is
almost unchanged wrt Calcite version).
> Reuse HiveRelFieldTrimmer instance across queries
> -------------------------------------------------
>
> Key: HIVE-22962
> URL: https://issues.apache.org/jira/browse/HIVE-22962
> Project: Hive
> Issue Type: Improvement
> Components: CBO
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Priority: Major
> Labels: pull-request-available
> Attachments: HIVE-22962.01.patch, HIVE-22962.02.patch,
> HIVE-22962.03.patch, HIVE-22962.04.patch, HIVE-22962.05.patch,
> HIVE-22962.06.patch, HIVE-22962.patch
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Currently we create multiple {{HiveRelFieldTrimmer}} instances per query.
> {{HiveRelFieldTrimmer}} uses a method dispatcher that has a built-in caching
> mechanism: given a certain object, it stores the method that was called for
> the object class. However, by instantiating the trimmer multiple times per
> query and across queries, we create a new dispatcher with each instantiation,
> thus effectively removing the caching mechanism that is built within the
> dispatcher.
> This issue is to reutilize the same {{HiveRelFieldTrimmer}} instance within a
> single query and across queries.
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