[jira] [Created] (HIVE-13330) ORC vectorized string dictionary reader does not differentiate null vs empty string dictionary

["Prasanth Jayachandran (JIRA)" <ji...@apache.org>]

Prasanth Jayachandran created HIVE-13330:
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             Summary: ORC vectorized string dictionary reader does not differentiate null vs empty string dictionary
                 Key: HIVE-13330
                 URL: https://issues.apache.org/jira/browse/HIVE-13330
             Project: Hive
          Issue Type: Bug
    Affects Versions: 2.0.0, 1.3.0, 2.1.0
            Reporter: Prasanth Jayachandran
            Assignee: Prasanth Jayachandran
            Priority: Critical


Vectorized string dictionary reader cannot differentiate between the case where all dictionary entries are null vs single entry with empty string. This causes wrong results when reading data out of such files. 

{code:title=Vectorization On}
SET hive.vectorized.execution.enabled=true;
SET hive.fetch.task.conversion=none;
select vcol from testnullorc3 limit 1;

OK
NULL
{code}

{code:title=Vectorization Off}
SET hive.vectorized.execution.enabled=false;
SET hive.fetch.task.conversion=none;
select vcol from testnullorc3 limit 1;

OK

{code}

The input table testnullorc3 contains a varchar column vcol with few empty strings and few nulls. For this table, non vectorized reader returns empty as first row but vectorized reader returns NULL. 




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