Dongjoon Hyun created SPARK-22329:
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Summary: Use NEVER_INFER for
`spark.sql.hive.caseSensitiveInferenceMode` by default
Key: SPARK-22329
URL: https://issues.apache.org/jira/browse/SPARK-22329
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 2.2.0
Reporter: Dongjoon Hyun
Priority: Critical
In Spark 2.2.0, `spark.sql.hive.caseSensitiveInferenceMode` has a critical
issue.
- SPARK-19611 uses `INFER_AND_SAVE` at 2.2.0 since Spark 2.1.0 breaks some Hive
tables backed by case-sensitive data files.
bq. This situation will occur for any Hive table that wasn't created by Spark
or that was created prior to Spark 2.1.0. If a user attempts to run a query
over such a table containing a case-sensitive field name in the query
projection or in the query filter, the query will return 0 results in every
case.
- However, SPARK-22306 reports this also corrupts Hive Metastore schema by
removing bucketing information (BUCKETING_COLS, SORT_COLS) and changing owner.
- Since Spark 2.3.0 supports Bucketing, BUCKETING_COLS and SORT_COLS look okay
at least. However, we need to figure out the issue of changing owners. Also, we
cannot backport bucketing patch into `branch-2.2`. We need more tests on before
releasing 2.3.0.
Hive Metastore is a shared resource and Spark should not corrupt it by default.
This issue proposes to recover that option back to `NEVER_INFO` like Spark
2.2.0 by default. Users can take a risk by enabling `INFER_AND_SAVE` by
themselves.
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