SSAS Tabular - Memory Usage Behaviour

Can anyone please tell me about the memory usage behavior of SSAS 2012 Tabular model.

1. Does SSAS brings the entire database (all tables) in memory after processing or it brings selective data as per the user query pattern? If it doesn't bring the entire database in memory by default, how to configure it to do exactly this as I have a dedicated SSAS Tabular server and would like to bring the entire database in memory to speed up queries.
2. Any links, blogs around memory behavior configuration, settings, best practices.

Any help appreciated.

Thanks, Ashish Singh