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From "Chaoyu Tang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-8485) HMS on Oracle incompatibility
Date Wed, 10 Dec 2014 16:50:12 GMT

    [ https://issues.apache.org/jira/browse/HIVE-8485?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14241366#comment-14241366
] 

Chaoyu Tang commented on HIVE-8485:
-----------------------------------

Debugging into the Hive code, I did see that Hive persists the "" (empty string) but get it
back null despite that datanucleus.rdbms.persistEmptyStringAsNull is set to false. The version
of DN (core) Hive uses is 3.2.10, and backend Oracle DB version is Oracle Database 11g Express
Edition Release 11.2.0.2.0 - 64bit Production. 
[~andy], the property did not work as expected in Hive and do you see anything I probably
missed here?

 

> HMS on Oracle incompatibility
> -----------------------------
>
>                 Key: HIVE-8485
>                 URL: https://issues.apache.org/jira/browse/HIVE-8485
>             Project: Hive
>          Issue Type: Bug
>          Components: Metastore
>         Environment: Oracle as metastore DB
>            Reporter: Ryan Pridgeon
>            Assignee: Chaoyu Tang
>
> Oracle does not distinguish between empty strings and NULL,which proves problematic for
DataNucleus.
> In the event a user creates a table with some property stored as an empty string the
table will no longer be accessible.
> i.e. TBLPROPERTIES ('serialization.null.format'='')
> If they try to select, describe, drop, etc the client prints the following exception.
> ERROR ql.Driver: FAILED: SemanticException [Error 10001]: Table not found <table name>
> The work around for this was to go into the hive metastore on the Oracle database and
replace NULL with some other string. Users could then drop the tables or alter their data
to use the new null format they just set.



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