FreeDAC has a very powerful in-memory data storage engine. It's design is based on ADO.Net System.Data namespace architecture and outperforms it in many areas, including speed and memory usage.

Following diagram shows simplified object model of FreeDAC in-memory data storage engine:

Main features are:

• Solid, flexible, extendable object model
• Multiple tables in single storage
• Relations between tables
• Constraints on tables, including foreign keys with cascading actions
• Multiple views on single table
• Ability to direct use storage engine in application code