Abstract: A reservation system for making reservations in a shared memory buffer to store information from applications is logically partitioned in a number of fixed size indexed contiguous slots. The reservation system uses an atomic counter that is stored in the shared memory buffer. The value of the atomic counter can be associated with the index of a slot available for reservation. An application making a reservation increases the atomic counter value on a number of reserved slots to provide a value that is associated with the index of the next slot available for reservation. After the reservation is accomplished, the information is written into the reserved slots. The reservation system writes parsing information for further parsing to validate information in the shared memory buffer. The reservation system provides functionality for continuous and instantaneous dumping of the shared memory buffer into a file for cleaning and for wrapping the buffer.

Abstract: The use of a centralized version table allows for efficient object switching. Rather than synchronizing all database agents to recognize a newly created file as containing the most recent version of a given object, database agents requiring access to the given object need only consult the centralized version table to learn file identity information. That is, the database agents consult the centralized version table to determine which of the files associated with a given object contain the most recent version of the given object. Mechanisms associated with the use of the centralized version table also provide for efficient recovery from a failure that has occurred during an object switching transaction.

Abstract: A reservation system for making reservations in a shared memory buffer to store information from applications is logically partitioned in a number of fixed size indexed contiguous slots. The reservation system uses an atomic counter that is stored in the shared memory buffer. The value of the atomic counter can be associated with the index of a slot available for reservation. An application making a reservation increases the atomic counter value on a number of reserved slots to provide a value that is associated with the index of the next slot available for reservation. After the reservation is accomplished, the information is written into the reserved slots. The reservation system writes parsing information for further parsing to validate information in the shared memory buffer. The reservation system provides functionality for continuous and instantaneous dumping of the shared memory buffer into a file for cleaning and for wrapping the buffer.

Abstract: A technique for recovering a dropped table is provided. One or more table spaces are specified prior to one or more tables being dropped from the specified one or more table spaces. When a table is to be dropped from the one or more specified table spaces, a table identifier, a time stamp, and table definition attributes are stored for the dropped table in a data structure and the table is dropped. Upon receiving a request to restore a table space from the one or more specified table spaces, each of the one or more tables in the table space being restored is recovered using the data structure.

Abstract: A database management system having a dropped table recovery flag. If the dropped table recovery flag is on at the time that a table is dropped, an entry will be made in a dropped table history file. The dropped table history file contains a timestamp of the time of table drop, a unique dropped table identifier, and table definition information. The system includes a command to permit the table-space of a dropped table to be restored and rolled forward to the point of the dropped table drop. The restored and rolled forward dropped table data is written to a flat file. The flat file data is loaded into a recreated table in the current table space to recover the dropped table.

Abstract: A method executed by a data processor for scanning a reverse range. The scan is conducted in an index for a table having an upper end and a lower end. The reverse range has a start key value for defining the reverse range, and the index has a set of keys representing a set of records and record attributes in the table. Each key in the set of keys has a RID designating a record in the table and a key value corresponding to an attribute of the record in the table. The method includes the steps of searching the index for a start key, selecting an upper bound of the reverse range, and, if the upper bound is the first key in the index, indicating that the index does not contain any key value within the reverse range, or, if the upper bound is not the first key in the index, then fetching each key below the upper bound in the index.