[HADOOP-6711] Configuration should support list of values

• Type: New Feature
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: conf
• Assignee: Unassigned
• Reporter: Amar Kamat
• Created: 16/Apr/10 06:32
• Updated: 16/Apr/10 21:26

Description

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

// 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);

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.