Stamatis Zampetakis created HIVE-23768:
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             Summary: Metastore's update service wrongly strips partition 
column stats from the cache
                 Key: HIVE-23768
                 URL: https://issues.apache.org/jira/browse/HIVE-23768
             Project: Hive
          Issue Type: Bug
            Reporter: Stamatis Zampetakis
            Assignee: Stamatis Zampetakis


Metastore's update service wrongly strips partition column stats from the cache 
in an attempt to update them. The issue may go unnoticed since missing stats do 
not lead to query failures. 

However, they can alter significantly the query plan affecting performance. 
Moreover, they lead to flakiness since some times the stats are present and 
sometimes are not leading to a query that has a different plan overtime. 

Normally missing elements from the cache shouldn't be a correctness problem 
since we can always fallback to the raw stats. Unfortunately, there are many 
interconnections with other parts of the code (e.g., code to obtain aggregate 
statistics) where this contract breaks.   



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