I believe BigTable implements the kind of indexing they like. Re the point of scalability; while we don't really know how well MapReduce scales, usage at Googl

I believe BigTable implements the kind of indexing they like. Re the point of scalability; while we don't really know how well MapReduce scales, usage at Google provides good hints that it does so well. Further, I don't think relational databases scale linearly either, and it is notoriously difficult to implement large DB clusters.