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From "Sushanth Sowmyan (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-8485) HMS on Oracle incompatibility
Date Mon, 26 Jan 2015 23:31:35 GMT

     [ https://issues.apache.org/jira/browse/HIVE-8485?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sushanth Sowmyan updated HIVE-8485:
-----------------------------------
    Release Note: 
Introduces a new hive-site.xml parameter  : "hive.metastore.orm.retrieveMapNullsAsEmptyStrings"
that defaults to false.
For operation with oracle, or any other datastore that converts empty strings to nulls, users
should set this to true.

If this parameter is set to true, ObjectStore will transform any null map values it finds
in any of the parameters maps to "".
If this parameter is set to false, ObjectStore will prune any map entry where the value is
null.

  was:
Introduces a new hive-site.xml parameter  : "hive.metastore.orm.retrieveMapNullsAsEmptyStrings"
that defaults to false

For operation with oracle, or any other datastore that converts empty strings to nulls, we'd
set this to true, but by default, it'd be false.

If this parameter is set to true, ObjectStore will transform any null map values it finds
in any of the parameters maps to "".

If this parameter is set to false, ObjectStore will prune any map entry where the value is
null.


> 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: TODOC15
>         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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