MySQL was the biggest problem they had though! They brought in Lucene (Earlybird) that massively improved performance- which makes a lot of sense.(in addition t

MySQL was the biggest problem they had though! They brought in Lucene (Earlybird) that massively improved performance- which makes a lot of sense.(in addition to adding Cassandra and eventually manhattan). Then they started building a lot of things that weren't web applications, like RPC servers (where they created the finagle library) they ended up with a team where Scala and the JVM was more their area of expertise and interest and solution to every issue. No one thinks you use MySQL to build every kind of data application, no one thinks you use Rails to build every kind of server.