You can json or csv encode data in a streaming manner, you just need to escape some special characters (only " for csv) and add a separator. But I never worked

You can json or csv encode data in a streaming manner, you just need to escape some special characters (only " for csv) and add a separator. But I never worked on an application where log records were big enough for streaming to make sense. If you want to preserve the "one line = one record" property typically expected from logs, standard csv will not be suitable (since it doesn't escape linebreaks), but json without unnecessary linebreaks will handle that (known as json-lines).