International Business Machines Corporation

Ibm Canada Limited - Ibm Canada Limitee

Sean W McKeough

Timothy Jon Vincent

Matthew Albert Huras

Douglas James Doole

George M Wilson

Timothy J Vincent

Bishwaranjan Bhattacharjee

Timothy Ray Malkemus

Xun Xue

Keriley Kay Romanufa

Catherine Suzanne McArthur

Frank-Martin Haas

Nelson Hop Hing

Sherman Lau

Roger L Zheng

David Sciaraffa

Jo-anne Mona Louise Kirton

Torsten W E Ziegler

Melissa N Bousfield

Douglas J Doole

Matthew A Huras

Melissa Bousfield

Provided are techniques for reclamation of empty pages in database tables. In response to receiving a plurality of records for insertion into a database table, the plurality of records are inserted into one or more contiguous pages. In response to at least some of the plurality of records being deleted from the database table, the one or more contiguous pages are reclaimed by: relocating any records from the plurality of records remaining in the one or more contiguous pages and releasing the one or more contiguous pages.

Reclamation of empty pages in database tables

A method for recreating a plurality of database dependencies of objects from one database to another is disclosed. The method comprises categorizing the dependencies based upon at least one base object and formalizing the relationships of the dependencies based upon the categorization. The method includes determining the order of recreating the objects based upon the formalizing of the relationships of the dependencies. In a preferred embodiment, the method builds a Dependency Management Table (DMT) that describes the relationship of each object to a base-table. The DMT includes an entry for every object-to-object relationship, including the category of the relationship, and the nesting-level of the dependency from the base-table. Using this information, objects can be recreated in an order which ensures correct management of dependencies.

Method for representing and recreating object dependencies from one database system to another

A method and system utilizes a hierarchical bitmap structure to represent deleted data sets. Each level in the hierarchical bitmap structure may have progressively larger size and represent finer granularity of number of data blocks than its parent level. A method in one aspect may comprise allocating a first level bitmap having size equal to a register on a processor, each bit in the first level bitmap representing a plurality of blocks of data in a database, and allocating one or more pointers corresponding to said plurality of bits in the first level bitmap, said one or more pointers being allocated to point to a sub bitmap generated after a data block is deleted but before the index corresponding to the data block is cleaned.

Method and system for utilizing a hierarchical bitmap structure to provide a fast and reliable mechanism to represent large deleted data sets in relational databases

Library management for libraries of user-defined routines in a database system. Libraries are stored in a long-term storage device and loaded into working memory in the database system when routines in the libraries are to be executed. An unload thread is defined to carry out the process of unloading libraries from the working memory when such libraries are inactive. The unload thread becomes active on a defined timing interval. The unload thread accesses a hash table and a most recently used list to determine which of the loaded libraries is inactive and which of the libraries ought to be unloaded. The hash table maintains information as to which libraries have been accessed in the most recent past defined timing interval. The size of the most recently used list can be defined such that all libraries associated with the list are retained in working memory.

Management of user-defined routine libraries in database environments

A database management system provides for the execution of invokable user-defined routines. Applications specify user-defined routines as being threadsafe or not threadsafe and specify the language of user-defined routines. Execution of routines will be carried out dependent on the threadsafe characteristic of the routines and on the language of the routines. Routines are assigned to processes based on their language to have any given process execute routines of the same language. Routines that are specified to be threadsafe are executed in threads in a potentially multi-threaded process. Each routine that is specified to be not threadsafe is executed in a fenced-mode processes in which no other routine is being executed.

Mechanism for invocation of user-defined routines in a multi-threaded database environment

A system and method for managing deadlocks in a database management system (DBMS) for a demultiplexed database system. The DBMS supports applications that are capable of holding and retaining locks on database resources while disassociated from worker agents. The system and method includes an application scheduler for managing requests for access to the database, and a deadlock detector for identifying a deadlock. The application scheduler assigns one worker agent to an application requesting access to a database resource, assigns a flag to an application holding a lock on the database resource while disassociated from a worker agent, and in cooperation with the deadlock detector, resolves the deadlock between the application requesting access and the flagged application holding the lock.

System and method for deadlock management in database systems with demultiplexed connections

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Markham, Canada

Sean W McKeough