I've got ELK + filebeat installed and I have recently started filtering my syslogs differently with a SYSLOG5424LINE logstash filter, since the syslog priority was defaulting to notice. This created some new indices in my syslog documents in elastic search, in addition to correcting the syslog priority fields that were incorrectly defaulted to 'notice'.
Now all my newly-generated syslog documents have a bunch of new fields that my old documents from before the filter change don't have, and I don't think reindexing my old documents would work since I would need to delete the syslog priority field with the incorrect value and replace it with syslog5424_pri field.
So, I've read how to delete all documents from elasticsearch, but once I do that, how do I get filebeat to resend all those logs to ES? Will it have the same indices and mapping as the new logs ES is receiving right now?