I've seen various Logstash filter plugins customizing the document_id field in pipeline filters (e.g. the HELK project). I'm trying to make sense of the reason for doing this. Doesn't a unique document_id get applied automatically?
I'm thinking of the document_id as akin to a unique key in a RDBMS table just as a way to identify an individal record. Perhaps I just haven't discovered what the document_id is useful for beyond allowing the system to refer to the particular document.
New Elastic Stack user here. I apologize for such a beginner question.