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From "Steve Loughran (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HADOOP-6228) Configuration should allow storage of null values.
Date Tue, 01 Sep 2009 15:52:32 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-6228?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12749955#action_12749955
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Steve Loughran commented on HADOOP-6228:
----------------------------------------

I'd be reluctant to do this 
# it's hard to send null values over the wire using XML or JSON
# It's harder for other tools to handle.
# It becomes trickier for other data sources to provide configurations if there is null-ness
in there too
# It gets really complicated if you ever add cross-referencing of values. Does the NULL value
propagate, or does the string "NULL" travel around.
# It gets complex with inheritance. Believe me, I speak from experience here. If I define
a null value  and make it final, does it become impossible for anyone ever to define that
value?

Which situations are in there that you can't just get away with an empty string instead? 

> Configuration should allow storage of null values.
> --------------------------------------------------
>
>                 Key: HADOOP-6228
>                 URL: https://issues.apache.org/jira/browse/HADOOP-6228
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: conf
>            Reporter: Hemanth Yamijala
>
> Currently the configuration class does not allow null keys and values. Null keys don't
make sense, but null values may have semantic meaning for some features. Not storing these
values in configuration causes some arguable side effects. For instance, if a value is defined
in defaults, but wants to be disabled in site configuration by setting it to null, there's
no way to do this currently. Also, no track of keys with null values is recorded. Hence, tools
like dump configuration (HADOOP-6184) would not display these properties.
> Does this seem like a sensible use case ?

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