[jira] [Work logged] (HIVE-24403) change min_history_level schema change to be compatible with previous version

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

     [ https://issues.apache.org/jira/browse/HIVE-24403?focusedWorklogId=513756&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-513756 ]

ASF GitHub Bot logged work on HIVE-24403:
-----------------------------------------

                Author: ASF GitHub Bot
            Created on: 18/Nov/20 20:10
            Start Date: 18/Nov/20 20:10
    Worklog Time Spent: 10m 
      Work Description: pvargacl opened a new pull request #1688:
URL: https://github.com/apache/hive/pull/1688


   
   ### What changes were proposed in this pull request?
   Modify HIVE-23107 to make it backward compatible with older version HMS-s using the same backend DB
   
   
   ### Why are the changes needed?
   
   
   
   ### Does this PR introduce _any_ user-facing change?
   No
   
   
   ### How was this patch tested?
   Unit tests
   


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

            Worklog Id:     (was: 513756)
    Remaining Estimate: 0h
            Time Spent: 10m

> change min_history_level schema change to be compatible with previous version
> -----------------------------------------------------------------------------
>
>                 Key: HIVE-24403
>                 URL: https://issues.apache.org/jira/browse/HIVE-24403
>             Project: Hive
>          Issue Type: Improvement
>          Components: Metastore
>            Reporter: Peter Varga
>            Assignee: Peter Varga
>            Priority: Major
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> In some configurations the HMS backend DB is used by HMS services with different versions. 
>  HIVE-23107 dropped the min_history_level table from the backend DB making the new schema version incompatible with the older HMS services. 
>  It is possible to modify that change to keep the compatibility
>  * Keep the min_history_level table
>  * Add the new fields for the compaction_queue the same way
>  * Create a feature flag for min_history_level and if it is on
>  * Keep the logic inserting to the table during openTxn
>  * Keep the logic removing the records at commitTxn and abortTxn
>  * Change the logic in the cleaner, to get the highwatermark the old way
>  * But still change it to not start the cleaning before that
>  * The txn_to_write_id table cleaning can work the new way in the new version and the old way in the old version
>  * This feature flag can be automatically setup based on the existence of the min_history level table, this way if the table will be dropped all HMS-s can switch to the new functionality without restart



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