Re: Mapper and Reducer takes longer than usual for a HBase table aggregation task

[李洪忠]

You need release your map code here to analyze the question. generally, 
when map/reduce hbase,  scanner with filter(s) is used. so the mapper 
count is the hbase region count in your hbase table.
As the reason why you reduce so slow, I guess, you have an disaster join 
on the three tables, which cause too many rows.

于 2013/8/26 4:36, Pavan Sudheendra 写道:
Another Question, why does it indicate number of mappers as 1? Can i 
change it so that multiple mappers perform computation?