What would be the correct way to design a DAO which implementation is first going to be targeting a MS SQL database with a STAR model, but yet, business requirements specify the application must be flexible enough that it would be able to be migrated to a NoSQL database in the future if required. Which type of NoSQL, no idea...

My confusion is that i cannot seem to figure out how could I build independent DAOs for the STAR Dimensions and Facts tables which could then be swapped for a completely different model that might not even be table oriented (riak/mongo/whatever). 

Therefore,

Should I create DAOs which rather than abstracting the table, it abstracts the CRUD operations - for example create IDaoInsert which can then be implemented as SQLInsertDaoImpl and MongoInsertDaoImpl, each with a completely different model logic etc.

or

Should I just create the typical DAO design whose interface would be something like IDaoCustomerDimension, and the implementation SqlDaoCustomerDimesionImpl and MongoDaoCustomerDimentionImpl respectively?

Hibernate/Etc are out of the scope of this question for the time being.


Question: Black hole collision and the event horizon
Answer: Yes,

Like del piero says, the gravitational field of each one affects the shape of the other, so it's similar to the "metaballs" used in computer graphics.

The exact shape will depend on the geometry, but it usually looks like two fingers reaching out to meet, like in Michelangelo's "The Creation of Adam". You can really see it in the first &amp; last videos here, but there are some good videos of death spirals in between.

Note that the pulsing at the end of the first video isn't anything real; it's caused by the change in magnitude of the color scale shown in the bottom right corner. 

There are also a couple of decent still frames (head on collisions of equally massed holes) on these two pages: 1,2.

This one has a shot of asymmetrically massed black holes, just after they join (with the original event horizons drawn underneath):