> Generally any large social network will need to follow the 1 database per account strategy to some extent because of the tricky many-to-many relationship that

> Generally any large social network will need to follow the 1 database per account strategy to some extent because of the tricky many-to-many relationship that groups/users have with other groups/users- this creates a cartesian product that is too large to traverse in reasonable time with one large database. Once cartesian products start to reach certain sizes, a few trade-offs can be made. The compute cost of traversing complex entity relationships in a relational database can be mitigated by using denormalization—allowing lots of duplicates since storage is cheap. Another alternative is to switch to a network database so entity relationships can be traversed using graph semantics.