This can be a confusing topic. Hadoop is several things. A No-SQL data store, map-reduce and a global file system. No-SQL and Map-Reduce can be quite valuable,

This can be a confusing topic. Hadoop is several things. A No-SQL data store, map-reduce and a global file system. No-SQL and Map-Reduce can be quite valuable, even on a single server. CouchDB runs on Android for example. If you don't need a global file system, use MariaDB, CouchDB or Mongo depending on your use-case.