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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