What about your total Map Task Capacity? you may check it from http://your_jobtracker:50030/jobtracker.jsp
2011/8/24 Daniel,Wu <hadoop...@163.com>: > I checked my setting, all are with the default value.So per the book of > "Hadoop the definitive guide", the split size should be 64M. And the file > size is about 500M, so that's about 8 splits. And from the map job > information (after the map job is done), I can see it gets 8 split from one > node. But anyhow it starts only one map task. > > > > At 2011-08-24 02:28:18,"Aggarwal, Vaibhav" <vagg...@amazon.com> wrote: > > If you actually have splittable files you can set the following setting to > create more splits: > > > > mapred.max.split.size appropriately. > > > > Thanks > > Vaibhav > > > > From: Daniel,Wu [mailto:hadoop...@163.com] > Sent: Tuesday, August 23, 2011 6:51 AM > To: hive > Subject: Why a sql only use one map task? > > > > I run the following simple sql > select count(*) from sales; > And the job information shows it only uses one map task. > > The underlying hadoop has 3 data/data nodes. So I expect hive should kick > off 3 map tasks, one on each task nodes. What can make hive only run one map > task? Do I need to set something to kick off multiple map task? in my > config, I didn't change hive config. > > > >
