I would like to group my data using data table visualization so that, if I take the example attached, for each same hostname I could have all the categories gathered in a raw and the corresponding count values summed up?.
pipe.skype.com =>Chat.., Internet Telephony
isee.europe.hp.com => Technology/Internet, URLs_...,URLs_UNIX_...,URLs_Windows_..
Another question, is there a way to rename the columns?
There isn't currently a way to do that that I can think of. The best I can think of right now is adding another table (or chart) with only a terms aggregation on host.raw if you need the combined counts.
Metric/column labels are available in 4.5+, https://github.com/elastic/kibana/pull/6123
If you are still struggling with this, I recommend that you build a custom visualization (Plugin).
It's not that hard, I can give some pointers, or you can check out examples at my github (https://github.com/JuanCarniglia).
If you need/want I can develop this visualization for you.
Let me know, I hope this helps.