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https://issues.apache.org/jira/browse/HIVE-27586?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stamatis Zampetakis updated HIVE-27586:
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Attachment: cast_string_date_hive_versions.svg
> Parse dates from strings ignoring trailing (potentialy) invalid chars
> ---------------------------------------------------------------------
>
> Key: HIVE-27586
> URL: https://issues.apache.org/jira/browse/HIVE-27586
> Project: Hive
> Issue Type: Improvement
> Components: HiveServer2
> Affects Versions: 4.0.0-beta-1
> Reporter: Stamatis Zampetakis
> Assignee: Stamatis Zampetakis
> Priority: Major
> Labels: backwards-compatibility, pull-request-available
> Fix For: 4.0.0
>
> Attachments: cast_string_date_hive_versions.pdf,
> cast_string_date_hive_versions.svg
>
>
> The goal of this ticket is to extract and return a valid date from a string
> value when there is a valid date prefix in the string.
> The following table contains a few illustrative examples highlighting what
> happens now and what will happen after the proposed changes to ignore
> trailing characters. HIVE-20007 introduced some behavior changes around this
> area so the table also displays what was the Hive behavior before that change.
> ||ID||String value||Before HIVE-20007||Current behavior||Ignore trailing
> chars||
> |1|2023-08-03_16:02:00|2023-08-03|null|2023-08-03|
> |2|2023-08-03-16:02:00|2023-08-03|null|2023-08-03|
> |3|2023-08-0316:02:00|2024-06-11|null|2023-08-03|
> |4|03-08-2023|0009-02-12|null|0003-08-20|
> |5|2023-08-03 GARBAGE|2023-08-03|2023-08-03|2023-08-03|
> |6|2023-08-03TGARBAGE|2023-08-03|2023-08-03|2023-08-03|
> |7|2023-08-03_GARBAGE|2023-08-03|null|2023-08-03|
> This change partially (see example 3 and 4) restores the behavior changes
> introduced by HIVE-20007 and at the same time makes the current behavior of
> handling trailing invalid chars more uniform.
> This change will have an impact on various Hive SQL functions and operators
> (+/-) that accept dates from string values. A partial list of affected
> functions is outlined below:
> * CAST (V AS DATE)
> * CAST (V AS TIMESTAMP)
> * TO_DATE
> * DATE_ADD
> * DATE_DIFF
> * WEEKOFYEAR
> * DAYOFWEEK
> * TRUNC
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