[jira] [Commented] (HIVE-21002) Backwards incompatible change: Hive 3.1 reads back Avro and Parquet timestamps written by Hive 2.x incorrectly

["Owen O'Malley (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-21002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16740856#comment-16740856 ] 

Owen O'Malley commented on HIVE-21002:
--------------------------------------

The behavior of Avro and Parquet is wrong both in 2.x and 3.1. The path forward should be to match the desired Hive semantics and return '00:00:00' for new files, regardless of format.

Iceberg uses Parquet's isAdjustedToUTC = true for timestamptz, which is the equivalent of Hive's timestamp with local time zone and isAdjustedToUTC = false for timestamp. It would be good to match those semantics in Hive. Can we detect the version of Hive that wrote the Parquet file to provide compatibility with told files?

> Backwards incompatible change: Hive 3.1 reads back Avro and Parquet timestamps written by Hive 2.x incorrectly
> --------------------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-21002
>                 URL: https://issues.apache.org/jira/browse/HIVE-21002
>             Project: Hive
>          Issue Type: Bug
>    Affects Versions: 3.1.0, 3.1.1
>            Reporter: Zoltan Ivanfi
>            Priority: Major
>
> Hive 3.1 reads back Avro and Parquet timestamps written by Hive 2.x incorrectly. As an example session to demonstrate this problem, create a dataset using Hive version 2.x in America/Los_Angeles:
> {code:sql}
> hive> create table ts_‹format› (ts timestamp) stored as ‹format›;
> hive> insert into ts_‹format› values (*‘2018-01-01 00:00:00.000’*);
> {code}
> Querying this table by issuing
> {code:sql}
> hive> select * from ts_‹format›;
> {code}
> from different time zones using different versions of Hive and different storage formats gives the following results:
> |‹format›|Time zone|Hive 2.x|Hive 3.1|
> |Avro and Parquet|America/Los_Angeles|2018-01-01 *00*:00:00.0|2018-01-01 *08*:00:00.0|
> |Avro and Parquet|Europe/Paris|2018-01-01 *09*:00:00.0|2018-01-01 *08*:00:00.0|
> |Textfile and ORC|America/Los_Angeles|2018-01-01 00:00:00.0|2018-01-01 00:00:00.0|
> |Textfile and ORC|Europe/Paris|2018-01-01 00:00:00.0|2018-01-01 00:00:00.0|
> *Hive 3.1 clearly gives different results than Hive 2.x for timestamps stored in Avro and Parquet formats.* Apache ORC behaviour has not changed because it was modified to adjust timestamps to retain backwards compatibility. Textfile behaviour has not changed, because its processing involves parsing and formatting instead of proper serializing and deserializing, so they inherently had LocalDateTime semantics even in Hive 2.x.



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