Some slides that will be presented at the Graph Algortihms Building Blocks (GABB) meeting
can be found at: http://www.graphanalysis.org/workshop2014.html http://www.graphanalysis.org/IPDPS2014-workshop/140401-SparseMatrixSchemas.pptx
Slide 7 depicts the Common Big Data Archiecture
Slide 18 & 19 shows how various SQL queries map onto the D4M Schema.
This may be helpful for figuring out how to do SQL on Accumulo.
I think SQL on Accumulo for arbitrary schemas will be hard.
SQL on Accumulo for specific schemas should be fairly straightforward.