I noticed that too. I don't want to gainsay the author's experiences, but it sounds like the author is describing the job of a data analyst who happens to dabbl

I noticed that too. I don't want to gainsay the author's experiences, but it sounds like the author is describing the job of a data analyst who happens to dabble with various software. I don't get the sense the author has in-depth knowledge about the tools he lists. Also, I don't know about putting Mongo and Cassandra under "Tools for working with unusual datasets".