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From "Sushanth Sowmyan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-8485) HMS on Oracle incompatibility
Date Fri, 23 Jan 2015 22:00:36 GMT

    [ https://issues.apache.org/jira/browse/HIVE-8485?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14290065#comment-14290065
] 

Sushanth Sowmyan commented on HIVE-8485:
----------------------------------------

[~ctang.ma] : Thanks for your comment! I considered auto-enabling this flag if we detect oracle,
but I think we will wind up having too many corner cases of if-this-then-that in our code
if we go down that path, and having a config variable that we simply ask all oracle users
to set is cleaner, I thought. Also, with this patch, Oracle also does "work" out of the box,
it just chooses the strategy of trimming by default, as is done in all other dbs.

Also, if we wanted to support nulls inside the maps, that would be a change in hive behaviour
(for the better, I'd think, but a behaviour change nonetheless) if we supported nulls. We'd
have to handle escaping over thrift maps, but it could be done.

Multiple spaces already work and is valid, just maybe not for a delim parameter, but there's
nothing stopping a user from having an arbitrary other parameter be multiples of spaces, either
in oracle or elsewhere.

> 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
>         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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