Lucent Technologies Inc.

Philip Lewis Bohannon

Abraham Silberschatz

Rajeev R Rastogi

Sundararajarao Sudarshan

Daniel Francis Lieuwen

Srinivasan Seshadri

Dennis W Leinbaugh

James Allen Parker

For use with a database of data records stored in a memory, a system and method for increasing a memory capacity and a memory database employing the system or the method. The system includes: (1) a time stamping controller that assigns a time stamp to transactions to be performed on the database, the time stamp operates to preserve an order of the transactions, (2) a versioning controller that creates multiple versions of ones of the data records affected by the transactions that are update transactions and (3) an aging controller, which is associated with each of the time stamping and versioning controllers, that monitors a measurable characteristic of the memory and deletes ones of the multiple versions of the ones of the data records in response to the time stamp and the measurable characteristic thereby to increase memory capacity.

System and method for aging versions of data in a main memory database

A method for recovering spin locks in a system having one or more processes capable of accessing a shared resource, the system providing a lock indicating exclusive access to the shared resource by a single process and enabling one or more processes to repeatedly attempt to gain access to the lock when ownership of the shared resource is desired. The method includes generating a linked list queue structure containing a first process currently having exclusive access to the lock and one or more processes added to the queue structure to spin on the lock, each process capable of modifying the queue structure by obtaining exclusive access of the lock from a process having exclusive access of the lock and releasing the lock to another process in the linked list queue structure; detecting when one or more processes having exclusive access to the lock terminates, and upon detection, removing the terminated process from the queue structure, and restoring consistency to said linked list queue structure.

Recoverable spin lock system

For use with an active database stored in volatile memory for direct revision thereof, the active database having multiple checkpoints and a stable log, having a tail stored in the volatile memory, for tracking revisions to the active database to allow corresponding revisions to be made to the multiple checkpoints, the active database subject to corruption, a system for, and method of, restoring the active database and a computer system containing the same. The system includes: (1) a checkpoint determination controller that determines which of the multiple checkpoints is a most recently completed checkpoint and copies the most recently completed checkpoint to the volatile memory to serve as an unrevised database for reconstructing the active database and (2) a revision application controller that retrieves selected ones of the revisions from the stable log and the tail and applies the revisions to the unrevised database thereby to restore the active database. In an advantageous embodiment, the applied revisions include log records at an operation level (lower level of abstration than transactions), and the revision application controller, using memory locks while restoring the active database, releases ones of the memory locks as a function of applying ones of the log records.

System and method for restoring a multiple checkpointed database in view

For use with a central database associated with a server of a network, the central database having distributed counterparts stored in volatile memories of clients of the network to allow operations to be performed locally thereon, the central database further having multiple checkpoints and a stable log stored in the server for tracking operations on the central database to allow corresponding operations to be made to the multiple checkpoints, the stable log having tails stored in the volatile memories to track operations on corresponding ones of the distributed counterparts, the distributed counterparts to corruption, a system for, and method of, restoring a distributed counterpart stored in one of the volatile memories. The system includes: (1) a checkpoint determination controller that determines which of the multiple checkpoints is a most recently completed checkpoint and copies the most recently completed checkpoint to the one of the volatile memories to serve as an unrevised database for reconstructing the distributed counterpart and (2) an operation application controller that retrieves selected ones of the operations from the stable log and a tail corresponding to the distributed counterpart and applies the operations to the unrevised database thereby to restore the distributed counterpart.

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Mt. Tabor, NJ, United States of America

Philip Lewis Bohannon