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Posted to common-user@hadoop.apache.org by Sandhya E <sa...@gmail.com> on 2009/01/08 13:13:30 UTC
OutputCollector to print only keys
Hi
Does Hadoop 0.18 have an outputcollector that can print out only the
keys and supress the values. In our case we need only the keys, and
hence we do output.collect(key, blank) and then reprocess the entire
output file to remove trailing tabs.
Can this be done more cleanly through the hadoop classes itself.
Many Thanks in Advance
Sandhya
Re: OutputCollector to print only keys
Posted by Owen O'Malley <om...@apache.org>.
On Jan 8, 2009, at 4:13 AM, Sandhya E wrote:
> Does Hadoop 0.18 have an outputcollector that can print out only the
> keys and supress the values. In our case we need only the keys, and
> hence we do output.collect(key, blank) and then reprocess the entire
> output file to remove trailing tabs.
If you are using TextOutputFormat, you can either emit NullWritables
or null. So do:
output.collect(key, null);
and it should work fine.
-- Owen
Re: OutputCollector to print only keys
Posted by Owen O'Malley <om...@apache.org>.
On Jan 8, 2009, at 4:13 AM, Sandhya E wrote:
> Does Hadoop 0.18 have an outputcollector that can print out only the
> keys and supress the values. In our case we need only the keys, and
> hence we do output.collect(key, blank) and then reprocess the entire
> output file to remove trailing tabs.
If you are using TextOutputFormat, you can either emit NullWritables
or null. So do:
output.collect(key, null);
and it should work fine.
-- Owen