[jira] [Created] (SPARK-31892) Disable week-base date filed for parsing

["Kent Yao (Jira)" <ji...@apache.org>]

Kent Yao created SPARK-31892:
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             Summary: Disable week-base date filed for parsing
                 Key: SPARK-31892
                 URL: https://issues.apache.org/jira/browse/SPARK-31892
             Project: Spark
          Issue Type: Sub-task
          Components: SQL
    Affects Versions: 3.0.0, 3.1.0
            Reporter: Kent Yao


It's an un-fixable behavior change to fill the gap between SimpleDateFormat and DateTimeFormater and backward-compatibility for different JDKs.

A lot of effort has been made to prove this at https://github.com/apache/spark/pull/28674

The existing behavior itself in 2.4 is confusing, e.g. 

{code:sql}
spark-sql> select to_timestamp('1', 'w');
1969-12-28 00:00:00
spark-sql> select to_timestamp('1', 'u');
1970-01-05 00:00:00
{code}

the 'u' here seems not to go to the Monday of the first week in week-based form or the first day of the year in non-week-based form but go to the Monday of the second week in week-based form.


{code:sql}
spark-sql> select to_timestamp('2020 2020', 'YYYY yyyy');
2020-01-01 00:00:00
spark-sql> select to_timestamp('2020 2020', 'yyyy YYYY');
2019-12-29 00:00:00
spark-sql> select to_timestamp('2020 2020 1', 'YYYY yyyy w');
NULL
spark-sql> select to_timestamp('2020 2020 1', 'yyyy YYYY w');
2019-12-29 00:00:00
{code}

I think we don't need to introduce all the weird behavior from Java.




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