Consider mapping of XDI operations to DB operations

[peacekeeper]

• Does the DB provide write operations that align well with XDI operations?
  • Can $set be mapped to a single DB operation?
  • Can $add be mapped to a single DB operation?
  • Can $mod be mapped to a single DB operation?
• Does the DB provide suitable read operations?
  • Can an entire subgraph be retrieved using a single DB operation?
• Can multiple XDI operations be queued sent to the DB in a single transaction?
• Graph API layer uses a boolean “hint” for getXXX() calls to tell its implementations whether the entire subgraph is needed