The architecture of the Dali main-memory storage manager

Performance needs of many database applications dictate that the entire database be stored in main memory. The Dali system is a main memory storage manager designed to provide the persistence, availability and safety guarantees one typically expects from a disk-resident database, while at the same time providing very high performance by virtue of being tuned to support in-memory data. User processes map the entire database into their address space and access data directly, thus avoiding expensive remote procedure calls and buffer manager interactions typical of accesses in disk-resident commercial systems available today. Dali recovers the database to a consistent state in the case of system as well as process failures. It also provides unique concurrency control and memory protection features, as well as ordered and unordered index structures. Both object-oriented and relational database management systems have been implemented on top of Dali. Dali provides access to multiple layers of application programming interface, including its low-level recovery, concurrency control and indexing components as well as its high-level relational component. Finally, various features of Dali can be tailored to the needs of an application to achieve high performance-for example, concurrency control and logging can be turned off if not desired, enabling Dali to efficiently support applications that require non-persistent memory-resident data to be shared by multiple processes.