Abstract: Disclosed is an evaluation technique for text search with black-box scoring functions, where it is unnecessary for the evaluation engine to maintain details of the scoring function. Included is a description of a system for dealing with blackbox searching, proofs of correctness, as well experimental evidence showing that the performance of the technique is comparable in efficiency to those techniques used in custom-built engines.

Abstract: A method and system for controlling concurrency of access to data in a database system, includes: partitioning a table in the database system into a plurality of partitions; receiving a request for access to data; determining a partition of the plurality of partitions that contains the data; determining if the data has been committed; and if so, avoiding locking the partition in response to the request. By avoiding locking the partition when the data has been committed, the number of partition locks that need to be requested from a local resource lock manager is reduced, improving performance.

Abstract: Database tables which are to be loaded with large data objects are defined with a special logging attribute that causes the associated database management system to suspend recovery logging for the databases so defined, but to continue with logging control information, such as space management changes. During a two-phase commit operation for a database transaction in a distributed system, at each database all modified data pages are written to disk before the end of the phase 1 commit, if the pages have not been previously written. This and other write operations are monitored for errors. If any of the changed data pages cannot be written to disk successfully before the end the phase 1 commit operation, then the transaction is rolled back at all databases.

Abstract: Database tables which are to be loaded with large data objects (LOBs) are defined with a special logging attribute value. This attribute value causes the database management system to suspend recovery logging for the databases so defined, but to continue with the logging of control information, such as space management changes. Certain control information recovery log entries have a special status indicator. For LOBs, this status indicator is set to cause the associated LOB entry to be marked as invalid when the log entry is reapplied, for example, during a recovery operation from a media failure. Rather than invalidating the entire table, the database management system will only prevent access to the entries which have been invalidated during the recovery process.

Abstract: A system, method and computer readable medium containing programming structions for an improved latch mechanism for use in a programming environment running concurrent tasks is disclosed. According to one aspect of the present invention, a latch is provided to a first task which is requesting access to a resource. After such access, the first task holds the latch, which is also released from the first task. The first task holding the latch marks the latch stealable, and if the latch is not marked stolen by another task, the first task can mark the latch unstealable. In another embodiment of the present invention, if the first task is provided a latch marked stealable, the resource associated with the stealable latch will be placed in a consistent state before the first task accesses the resource.

Abstract: The present invention provides a system and method for utilizing the proximity of keys in sequential or near sequential index probes to avoid complete index tree traversal. Page information from three pages (LAST, PARENT and NEXT) are stored in separate information fields within an Index Lookaside Buffer. The LAST information field contains information on the most recent leaf page accessed during an index probe in a read key or an insert key operation, the PARENT information field contains information on the parent page of the most recently accessed leaf page described in the LAST information field, and the NEXT information field contains information on the most recent leaf page accessed during a fetch-next key or delete key operation.

Abstract: The present invention provides a system and method for utilizing the proximity of keys in sequential or near sequential index probes to avoid complete index tree traversal. Page information from three pages (LAST, PARENT and NEXT) are stored in separate information fields within an Index Lookaside Buffer. The LAST information field contains information on the most recent leaf page accessed during an index probe in a read key or an insert key operation, the PARENT information field contains information on the parent page of the most recently accessed leaf page described in the LAST information field, and the NEXT information field contains information on the most recent leaf page accessed during a fetch-next key or delete key operation.