I am preparing upgrade elastic stack from 2.3 to 5.2.
My question is...
Index dailylog.20170311(created by es 2.3) has string field "subject".
what happen if dailylog.20170312(will created by es 5.2) will have keyword or text field "subject"?
usually kibana complains type conflict.
What about this case? do I need to reindex 20170311 before serving?