"J48 algorithm"

Hello,

I am a beginner in working with data mining, so I would really appreciate your help. I have a dataset with approximately  million entries. I ran the split validation with using the j48 algorithm and still didn't get any results and the programme has been runing for 4 days already. So can anyone tell me, if I should hope for results or all of this was just in vain and there is some more efficient way to get the results.

Thanks in advance
Bojana