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From "Shannon Ladymon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-8485) HMS on Oracle incompatibility
Date Fri, 22 Jul 2016 23:41:20 GMT

    [ https://issues.apache.org/jira/browse/HIVE-8485?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15390365#comment-15390365
] 

Shannon Ladymon commented on HIVE-8485:
---------------------------------------

Th parameter *hive.metastore.orm.retrieveMapNullsAsEmptyStrings* has been documented in the
wiki:
* [Configuration Properties - hive.metastore.orm.retrieveMapNullsAsEmptyStrings | https://cwiki.apache.org/confluence/display/Hive/Configuration+Properties#ConfigurationProperties-hive.metastore.orm.retrieveMapNullsAsEmptyStrings]

A link to the parameter has also been included in the Oracle section of the Supported Backend
Databases for Metastore:
* [AdminManual MetastoreAdmin - Supported Backend Databases for Metastore | https://cwiki.apache.org/confluence/display/Hive/AdminManual+MetastoreAdmin#AdminManualMetastoreAdmin-SupportedBackendDatabasesforMetastore]

> 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: Sushanth Sowmyan
>              Labels: TODOC1.0, TODOC15
>             Fix For: 1.0.0
>
>         Attachments: HIVE-8485.2.patch, HIVE-8485.patch
>
>
> 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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