Abstract: Provided is a method for online reorganization and increasing the page size of a DB2 object. A base table and related auxiliary table spaces are reorganized concurrently via a database utility, DB2 REORG utility. The database utility determines which auxiliary tables are related to the base table and automatically includes their respective auxiliary table in the same invocation of the utility. The reorganization is performed via allocated shadow data sets; page size of the allocated shadow data sets is dynamically updated during reorganization. The original data sets are switched with the newly built shadow data sets, and DB2 catalog values and control blocks are updated with new page size values.

Abstract: A new sub-document versioning method for record storages of XML documents which uses virtual cutting points to ensure that a search tree is able to support multiple versions of sub-documents and provide efficient mechanisms for XML updating. Record boundaries and virtual cut points divide the two-dimensional space, the horizontal axis representing node identifiers in document order and vertical axis representing version numbers, into rectangles. The bottom corner of the rectangle is used to represent the rectangles and the corresponding information of the corner is added to the search tree index.

Abstract: A method for performing a system level backup of a log-ahead database management system (DBMS) without suspending updates by application programs is described. The DBMS comprises a database mainline system, a backup utility and a restore utility. The data and log records are stored on separate storage volumes. Log records are written to identify objects that require special handling during the point-in-time recovery. The database engine operates normally during a backup except for suspending actions that would alter the file system catalog or write updates across a storage volume boundary; and by freezing the REDO log point in its checkpoint information. The backup utility copies the data volumes first and optionally the log volumes second while updates are allowed. The resulting inconsistencies are resolved either during a DBMS restart or during a point-in-time (PIT) recovery performed by the restore utility.

Abstract: According to the present invention a method and a system is provided for establishing synchronized recovery log points in an infrastructure comprising at least a first database management system and a second database management system, whereby recovery log files are written and log points are created separately for each database management system. Firstly, log write of all database management systems is suspended, then, the corresponding log points for each database management system forming a global log point are recorded and log writes of all database management systems are resumed.

Abstract: A method and article of manufacture, implementing the method, allocates space for a dataset. The dataset has an initial area and zero or more additional allocated areas to provide space for storing the dataset. The size of a new additional area is determined. The new additional area is associated with a new area number, and the size of the new additional area is based on the new area number. Additional space for the dataset is allocated based on the size of the new additional area.

Abstract: A computer program product provides accurate statistics in real time. These statistics can be used to determine if a table space in a database management system (DBMS) requires maintenance operations such as reorganization, back up, fresh access path statistics, and/or larger disk space allocation. The DBMS maintains a set of values that provide indications of whether that operation is due on that object. The indicators are asynchronously externalized in dedicated database tables either periodically in user-specified intervals or at some predefined event such as stopping the database. When the user performs a database administration operation, the database management system resets the associated indicators, and reports objects that are in an exception state based on the indicators collected as described for each operation.

Abstract: According to the method, apparatus, and computer readable medium of the present invention, a scan is performed by accessing all rows of a table in a relational database, evaluating each row to determine whether the row satifies a set of predicates of a database query, and returning the row if it satisfies the set of predicates. According to a preferred embodiment of the present invention, all rows are evaluated regardless of current locks. The scan is continued if the row does not satisfy the set of predicates regardless of the current lock on the row. The locking semantics according to the invention has the advantage that it completely removes the problem of lock contention on the rows that do not satisfy statement predicates.

Abstract: In a database management system (DBMS) (60) for a database application (10) including a database (12) having a table (14, 16, 18) and a unique key index (42) having indexes (44, 46, 48) therefor, the DBMS (60) includes a data manager (64), an index manager (66), a transaction manager (62), and a lock manager (68) which restricts access to the table by assigning locks to elements thereof. In order to avoid deadlock in the database application due to the pseudo-deleted entries, the lock categories include an X-lock and a Conditional S-lock, and have lock attributes including at least a Delete attribute for the X-lock. The Conditional S-lock is compatible (granted by the lock manager) with an X-lock whose Delete attribute is NOT SET, but is not compatible (granted) with an X-lock whose Delete attribute is SET. Each index entry includes a pseudo-delete flag which is SET by the index manager (66) to indicate deletion of the indexed row.

Abstract: Traditional update semantics are provided when updates change the location of records in a database. The system detects that an update to a record will cause the record to change locations in a database from an original location to an updated location. The system selectively prevents activity in the database between the original location and update location until the updated record has changed locations in the database from the original location to the updated location.

Abstract: A method for performing a system level backup of a log-ahead database management system (DBMS) without suspending updates by application programs is described. The DBMS comprises a database mainline system, a backup utility and a restore utility. The data and log records are stored on separate storage volumes. Log records are written to identify objects that require special handling during the point-in-time recovery. The database engine operates normally during a backup except for suspending actions that would alter the file system catalog or write updates across a storage volume boundary; and by freezing the REDO log point in its checkpoint information. The backup utility copies the data volumes first and optionally the log volumes second while updates are allowed. The resulting inconsistencies are resolved either during a DBMS restart or during a point-in-time (PIT) recovery performed by the restore utility.

Abstract: A method and system for formatting space in a storage device for a database system is disclosed. The method and system include formatting a first increment for creating a database file and asynchronously formatting at least one subsequent increment for the database file in a background of the database system.

Abstract: According to the present invention a method and an system is provided for establishing synchronized recovery log points in an infrastructure comprising at least a first database management system and a second database management system, whereby recovery log files are written and log points are created separately for each database management system. Firstly, log write of all database management systems is suspended, then, the corresponding log points for each database management system forming a global log point are recorded and log writes of all database management systems are resumed.

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: A system and a method are described for selectively locking the partitions of a partitioned table in a relational database. The database system locks only those partitions of the table that are accessed by an application. Other partitions are available for concurrent access by other applications, regardless of the strength of the lock needed.

Abstract: A computer program product is provided as a system and associated method that provide accurate statistics in real time. These statistics can be used to determine if a table space in a database management system requires maintenance operations such as reorganization, back up, fresh access path statistics, and/or larger disk space allocation. The database management system or DBMS maintains a set of values that provide indications of whether that operation is due on that object. The objects for which the indicators are maintained depend on the specific DBMS. Typically, these objects are tables, indexes, and table spaces. The database management system maintains the indicators in memory. Some of the indicators are cumulative and others are given in absolute values. The indicators are asynchronously externalized in dedicated database tables either periodically in user-specified intervals or at some predefined event such as stopping the database.

Abstract: A method, apparatus, and article of manufacture for identifying read claims in a database. In accordance with the present invention, the database is stored on at least one data storage device connected to a computer. A read identifier is stored for each reading transaction. The read identifier reflects a time at which the reading transaction first accesses an object stored in the database. The read identifiers are used to determine an age of an oldest active transaction.

Abstract: Provided is a method, system, program, and data structures for making data available to an application program. A result table is generated including rows corresponding to a subset of rows in a base table having data in one or more columns that satisfy a query predicate clause. The result table includes, for each row, a location identifier of the corresponding row in the base table and a column for each column in a query select list. The result table is accessed to return requested data from the base table to the application program.

Abstract: Provided is a method, system, program, and data structures for making data available to an application program. A result table is generated including rows corresponding to a subset of rows in a base table having data in one or more columns that satisfy a query predicate clause. The result table includes, for each row, a location identifier of the corresponding row in the base table and a column for each column in a query select list. The result table is accessed to return requested data from the base table to the application program.

Abstract: A method, apparatus and article of manufacture for ensuring cache coherency in a database containing a data store on a central data storage device connected to a plurality of computers. When an immediate write option is set, the data in a local buffer pool changed by a first transaction on a first computer is immediately written to a group buffer pool at the central data storage device, prior to initiating a second transaction upon a second computer that relies upon the modified data. Local buffer pools are then invalidated thereby facilitating local buffer pool updates from the group buffer pool. The immediate write (IW) option may be a subsystem parameter set at a system level or a bind option set at a plan level. The immediate write option may be set so that data is written to the group buffer pool at or before a phase one commit.

Abstract: Coupling facility store-in cache structures are duplexed in order to improve data availability. That is, once duplexing is established, selective data is written to both a primary structure instance and a secondary structure instance. Thus, if one of the structure instances fails, then the other structure instance is used in order to prevent data from being lost. Duplexing can be started manually and/or automatically by the operating system. Further, a structure may be removed from duplex mode and enter simplex mode, if duplexing is not desired.