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Posted to common-issues@hadoop.apache.org by "Amar Kamat (JIRA)" <ji...@apache.org> on 2010/04/16 08:33:24 UTC
[jira] Created: (HADOOP-6711) Configuration should support list of
values
Configuration should support list of values
-------------------------------------------
Key: HADOOP-6711
URL: https://issues.apache.org/jira/browse/HADOOP-6711
Project: Hadoop Common
Issue Type: New Feature
Components: conf
Reporter: Amar Kamat
Configuration supports 2 operations namely _set()_ and _get()_. It would be nice to have an inbuild support for lists where there can be multiple values (i.e list of values) assigned to one key. A workaround could be
{code}
// Assume Key be the parameter key and newValue be the value to be added/appended
Configuration c = new Configuration();
String value = c.get(Key);
value = value + " " + newValue
c.set(Key, value);
{code}
One common usecase is that in a production enviroment, some user facing params (e.g mapred.child.java.opts) are set to default values (say for performance reasons). Users themselves might want to *add* to this list. Doing a set would overwrite the previous values. The above mentioned hack is doable via code but not via command line. Hence we need the framework to support lists.
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[jira] Commented: (HADOOP-6711) Configuration should support list
of values
Posted by "Jitendra Nath Pandey (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/HADOOP-6711?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12858010#action_12858010 ]
Jitendra Nath Pandey commented on HADOOP-6711:
----------------------------------------------
Configuration has a getStringCollection API : public Collection<String> getStringCollection(String name)
There is no such set method though.
> Configuration should support list of values
> -------------------------------------------
>
> Key: HADOOP-6711
> URL: https://issues.apache.org/jira/browse/HADOOP-6711
> Project: Hadoop Common
> Issue Type: New Feature
> Components: conf
> Reporter: Amar Kamat
>
> Configuration supports 2 operations namely _set()_ and _get()_. It would be nice to have an inbuild support for lists where there can be multiple values (i.e list of values) assigned to one key. A workaround could be
> {code}
> // Assume Key be the parameter key and newValue be the value to be added/appended
> Configuration c = new Configuration();
> String value = c.get(Key);
> value = value + " " + newValue
> c.set(Key, value);
> {code}
> One common usecase is that in a production enviroment, some user facing params (e.g mapred.child.java.opts) are set to default values (say for performance reasons). Users themselves might want to *add* to this list. Doing a set would overwrite the previous values. The above mentioned hack is doable via code but not via command line. Hence we need the framework to support lists.
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[jira] Commented: (HADOOP-6711) Configuration should support list
of values
Posted by "Hong Tang (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/HADOOP-6711?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12857913#action_12857913 ]
Hong Tang commented on HADOOP-6711:
-----------------------------------
A word of caution: the proposed implementation using string concatenation is inefficient when a user wants to add a lot of items on the list. I have been hit by this before when using FileInputFormat.addInputPath.
> Configuration should support list of values
> -------------------------------------------
>
> Key: HADOOP-6711
> URL: https://issues.apache.org/jira/browse/HADOOP-6711
> Project: Hadoop Common
> Issue Type: New Feature
> Components: conf
> Reporter: Amar Kamat
>
> Configuration supports 2 operations namely _set()_ and _get()_. It would be nice to have an inbuild support for lists where there can be multiple values (i.e list of values) assigned to one key. A workaround could be
> {code}
> // Assume Key be the parameter key and newValue be the value to be added/appended
> Configuration c = new Configuration();
> String value = c.get(Key);
> value = value + " " + newValue
> c.set(Key, value);
> {code}
> One common usecase is that in a production enviroment, some user facing params (e.g mapred.child.java.opts) are set to default values (say for performance reasons). Users themselves might want to *add* to this list. Doing a set would overwrite the previous values. The above mentioned hack is doable via code but not via command line. Hence we need the framework to support lists.
--
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