Mike Hillwig shows how to ignore columns with Logstash:
Like I said earlier, we have some data that I know I’ll never use. This is flight performance data. The dataset contains diversion information. If a flight gets diverted more than once, it’s tracked here. I don’t care about that, so I’m dropping the diversion information for the second through fifth diversions. I’m also dropping some information about the airports that I believe I won’t need. This is the tricky part. Somewhere down the road, I’m going to need to enhance this data by converting all of the times to UTC.
Mike’s slowly building up to a complete, working example and it’s interesting to watch the progress along the way.