if your data isn't relational to start with (e.g. messages in a message queue, being written to files in HDFS), you're better of with Map/Reduce
If you query the data once and then throw it away, then certainly load performance is a critical issue. If you load the data once and then query it many times, load performance is far less important -- trading a longer load time for much better query performance would be a good idea. So it depends on the workload as much as the format the data happens to start in.
If you query the data once and then throw it away, then certainly load performance is a critical issue. If you load the data once and then query it many times, load performance is far less important -- trading a longer load time for much better query performance would be a good idea. So it depends on the workload as much as the format the data happens to start in.