Traditional database management systems perform updates-in-place and use logs and periodic checkpointing to efficiently achieve atomicity and durability. In this Thesis we shall present a different method, Shades, for achieving atomicity and durability using a copy-on-write policy instead of updates-in-place. We shall also present index structures and the implementation of Shines, a persistent functional programming language, built on top of Shades. Shades includes real-time generational garbage collection. Real-timeness is achieved by collecting only a small part, a generation, of the database at a time. Contrary to previously presented persistent garbage collection algorithms, Shades has no need to maintain metadata (remembered sets) of intra-generation pointers on disk since the metadata can be reconstructed during recovery. This considerably reduces the amount of disk writing. In conjunction with aggressive commit grouping, efficient index structures, a design specialized to a main memory environment, and a carefully crafted implementation of Shines, we have achieved surprisingly high performance, handsomely beating commercial database management systems.

Reorganization of objects in an object databases is an important component of several operations like compaction, clustering, and schema evolution. The high availability requirements #24 # 7 operation# of certain application domains requires reorganization to be performed on-line with minimal intereference to concurrently executing transactions. In this paper, we address the problem of on-line reorganization in object databases, where a set of objects have to be migrated from one location to another. Speci#cally,we consider the case where objects in the database may contain physical references to other objects. Relocating an object in this case involves #nding the set of objects #parents# that refer to it, and modifying the references in each parent. We propose an algorithm called the Incremental Reorganization Algorithm #IRA# that achieves the above task with minimal interference to concurrently executing transactions. The IRA algorithm holds locks on at most two distinct objects at ...