[jira] [Work logged] (HIVE-27238) Avoid Calcite Code generation for RelMetaDataProvider on every query

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-27238?focusedWorklogId=855669&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-855669 ]

ASF GitHub Bot logged work on HIVE-27238:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 10/Apr/23 03:01
            Start Date: 10/Apr/23 03:01
    Worklog Time Spent: 10m 
      Work Description: scarlin-cloudera opened a new pull request, #4212:
URL: https://github.com/apache/hive/pull/4212

   …y query
   
   In the current code base, a new CachingRelMetadataProvider is created on every query.  This causes a cache miss within JaninoRelMetadataProvider, which stores the provider in the key. As a result, a new MetadataHandler is created multiple times in every query, which causes code generation and is a small hit on performance
   
   This commit caches HiveDefaultRelMetadataProviders globally which stores a RelMetadataProvider that can be reused. Ultimately, this class could most likely be removed as well, but this commit limits the scope of the change in a first pass.
   
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   Stated in commit message
   
   ### Why are the changes needed?
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   This will help performance and possibly have a smaller memory footprint.
   
   ### Does this PR introduce _any_ user-facing change?
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    No
   
   
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   This doesn't introduce new functionality, so current regression tests should be good. I ran this through the debugger and made sure the Calcite JaninoMetadataProvider.load3 method was not called after the first query was called with the same conf variables.
   




Issue Time Tracking
-------------------

            Worklog Id:     (was: 855669)
    Remaining Estimate: 0h
            Time Spent: 10m

> Avoid Calcite Code generation for RelMetaDataProvider on every query
> --------------------------------------------------------------------
>
>                 Key: HIVE-27238
>                 URL: https://issues.apache.org/jira/browse/HIVE-27238
>             Project: Hive
>          Issue Type: Improvement
>          Components: HiveServer2
>            Reporter: Steve Carlin
>            Priority: Major
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> In CalcitePlanner, we are instantiating a new CachingRelMetadataProvider on every query.  Within the Calcite code, they keep the provider key to prevent a new MetadataHandler class from being created.  But by generating a new provider, the cache never gets a hit so we keep instantiating new MetadataHandlers.



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