The reason spanner is a big deal is because it provides relational semantics including cross table transactions. That is why spanner is interesting. No one, no

The reason spanner is a big deal is because it provides relational semantics including cross table transactions. That is why spanner is interesting. No one, not even the most ambitious and clueless market folks at Cloudera, has ever sold Hadoop and MR type technologies as a replacement for RDBMs. Spanner can be used as a replacement. These two technologies don't solve the same problem. You still need MR to do analytics at scale on spanner!