Jason Dere created HIVE-19329:
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             Summary: Disallow some optimizations/behaviors for external tables
                 Key: HIVE-19329
                 URL: https://issues.apache.org/jira/browse/HIVE-19329
             Project: Hive
          Issue Type: Bug
            Reporter: Jason Dere
            Assignee: Jason Dere


External tables in Hive are often used in situations where the data is being 
created and managed by other applications outside of Hive. There are several 
issues that can occur when data being written to table directories by external 
apps:
- If an application is writing files to a table/partition at the same time that 
Hive tries to merge files for the same table/partition (ALTER TABLE 
CONCATENATE, or hive.merge.tezfiles during insert) data can be lost.
- When new data has been added to the table by external applications, the Hive 
table statistics are often way out of date with the current state of the data. 
This can result in wrong results in the case of answering queries using stats, 
or bad query plans being generated.

Some of these operations should be blocked in Hive. It looks like some already 
have been (HIVE-17403).



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