logstash-elasticsearch: sort data by timestamp

Question

I centralize logfiles into one logfile by using logstash and for each event I have timestamp(the original one). Now, my last challenge it to get this data sorted by timestamp(if possible on real-time thats better).

my timestamp format is: yyyy-MM-dd HH:mm:ss

Now, I can make any change in the format/ file format in order to make it work, as long as it stays on our servers.

What's the best way to sort my data? any ideas?

Thanks in advance!