Towards Multiverse Databases

Where an edge in the dataflow graph crosses a universe boundary, any necessary dataflow operators to enforce the required privacy policies are inserted. All applicable policies are applied on every edge that transitions into a given user universe, so whichever path data takes to get there we know the policies will have been enforced. The team compare the prototype with 5,000 active user universes, a MySQL implementation with inlined privacy policies (‘with AP’) and a MySQL implementation that does not enforce the privacy policy (‘without AP’):

Since the prototype is serving reads from a pre-computed universe stored in memory cached results are fast and make for a very favourable comparison against MySQL.

Source: blog.acolyer.org