Abstract: A method and system to manage temporary storage space of a relational database management system by receiving a data segment allocation request from an application, allocating a data segment to the application, marking the data segment as allocated in a space map page, and indicating a usage status of the data segment. The method also includes receiving a mass delete command from the application, indicating reception of the mass delete command in a table-related control block, and marking the data segment as unavailable in the space map page. The method may also include indicating reception of the mass delete commit command in the table-related control block to enable the application to reuse the data segment.

Abstract: A method, apparatus, and article of manufacture accesses a dataset using an unsupported access method. A first request to access a dataset is intercepted. The first request is associated with a first data structure that specifies a first access method. The first data structure is replaced with a second data structure that specifies a second access method which is different from the first access method. The dataset is accessed in accordance with the second access method of the second data structure. In another particular embodiment, the first access method is the basic direct access method, and the second access method is any of the basic sequential access method and the queued sequential access method. In yet another embodiment, the dataset is an extended format physical sequential dataset.

Abstract: The present invention is related to a method and system for preserving an original table schema for a table in a database system that supports dynamic table schema changes. The method and system includes storing the original table schema for the table in a designated table prior to performing a schema change on the table. By storing the original table schema in the designated table, a backup copy of the table that includes rows which are not self-describing can be used for data recovery.

Abstract: When recovering data in a database, initially, a database log, which records activities related to a database, is scanned. One or more individual objects that are to be recovered to a target time with reference to a backup time are identified.

Abstract: A method for ensuring referential integrity in a concurrent transaction database environment is disclosed. The method includes determining when an update to a dependent object requires special processing, and if special processing is required, locating and locking parent objects of the dependent object in share mode prior to committing the update to the dependent object.

Abstract: A method, apparatus, and article of manufacture accesses a dataset using an unsupported access method. A first request to access a dataset is intercepted. The first request is associated with a first data structure that specifies a first access method. The first data structure is replaced with a second data structure that specifies a second access method which is different from the first access method. The dataset is accessed in accordance with the second access method of the second data structure.

Abstract: A defer dataset creation system creates database objects at a computer connected to a data storage device. Initially, a command to create a database object is received. A database object definition for that database object is recorded. When the database object is accessed, a dataset for the database object is created from its database object definition.

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 and method for destaging changed data from a shared cache castout in a shared data environment distributes castout ownership for a dataset among a plurality of systems having an update interest in the dataset. One system is designated as having castout ownership of the dataset in a primary state. All other systems having an update interest in the dataset hold castout ownership for the dataset in a backup state. When the primary owner relinquishes ownership, primary ownership is passed to one of the backup systems. A structure castout owner for the entire cache assumes the responsibility of castout of changed data for a dataset for which the primary castout owner has had a failure.

Abstract: A computer program product for a system and method for destaging changed data from a shared cache castout in a shared data environment distributes castout ownership for a dataset among a plurality of systems having an update interest in the dataset. One system is designated as having castout ownership of the dataset in a primary state. All other systems having an update interest in the dataset hold castout ownership for the dataset in a backup state. When the primary owner relinquishes ownership, primary ownership is passed to one of the backup systems. A structure castout owner for the entire cache assumes the responsibility of castout out changed data for a dataset for which the primary castout owner has had a failure.

Abstract: A system and method are provided for recovering a computerized database. During transaction processing of a database, at least one log range is tracked comprising update transaction log records. The log range has a begin value and an end value. The begin value corresponds to a log RBA location of a first access of the database by an updating transaction. The end value corresponds to a log RBA location at a commit or abort of a last updating transaction. The end value corresponds to a point when the database is designated as being read only (called pseudo open). During recovery of the database, the update transaction log records in the log range are applied to a version of the database stored in non-volatile memory.

Abstract: An efficient procedure for determining the set of buffer pool database pages that must be externalized to stable storage and for scheduling their write I/O's before release of a committing transaction's locks. In a multisystem database management system (DBMS) with high-speed shared external storage (SES) environment, a DBMS instance may follow "force-at-commit" protocol for a database that has intersystem read/write interest or may alternatively follow a "no-force-at-commit" policy when operating with a database for which only one system has interest. By introducing the concept of a series of unique ordinal numbers (ORD#) for each database assigned to buffer pool data pages whenever the page state changes from clean to dirty within a single DBMS instance, this procedure maintains a transaction page list (TPL) for each transaction in ORD# order.

Abstract: A system and method are provided for recovering a computerized database. During transaction processing of a database, at least one log range is tracked comprising update transaction log records. The log range has a begin value and an end value. The begin value corresponds to a log RBA location of a first access of the database by an updating transaction. The end value corresponds to a log RBA location at a commit or abort of a last updating transaction. The end value corresponds to a point when the database is designated as being read only (called pseudo open). During recovery of the database, the update transaction log records in the log range are applied to a version of the database stored in non-volatile memory.

Abstract: A computer-implemented method for minimizing the amount of time to access current data in a database which may be stored wholly in a DASD-oriented external storage subsystem or partly in DASD and partly in a stored high-speed electronic store while maintaining coherency of the data with respect to multiple user systems.

Abstract: A method for ensuring data coherence while detecting whether the locally cached copy of a data page is invalid and responsively refreshing the locally cached page from a Shared Electronic Store (SES) in a multisystem shared disk environment. Locally cached data pages may become invalid in a multisystem shared disk environment because of transactions executed by other systems for the common database. Thus, whenever a transaction in a database management system (DBMS) instance desires to read or update a record in a locally cached data page, the DBMS must first verify validity for the locally cached copy and, for stale or invalid copies, must re-read and re-register the latest version in the SES. This invention provides a procedure for the necessary verification and refreshing steps that relies on page latching to serialize the combination of local multiuser and global multisystem activities. The procedure of this invention supports both record and page locking granularities.

Abstract: A computer-implemented method for minimizing the amount of time to access current data in a database which may be stored wholly in a DASD-oriented external storage subsystem or partly in DASD and partly in a stored high-speed electronic store while maintaining coherency of the data with respect to multiple user systems.

Abstract: In a multi-system data sharing complex, a database system can write updated pages to a shared electronic store for a fast write. Other database systems can obtain pages written to the shared store for further modification without the pages first being written to stable storage. However, pages are eventually written to the stable storage in a castout process. Recovery of a database from failure of the shared store is bounded by determination of a recovery boundary which, when applied to the union of database system transaction logs, establishes a point in front of which are found log records of modifications to pages which were in the shared store when it failed. These log records are applied to page versions obtained from stable storage to recover from failure of the shared store.

Abstract: A page-accessing method in a segmented tablespace 10 which eliminates unnecessary reading and locking. The tablespace comprises data pages 18 grouped into identically-sized segments 16, each segment storing data for a single table. A status indicator 26 for each data page of a segment is kept in a separate segment control block 20 stored on a space map page 14. Five data page status indicator values are maintained:(1) FULL (26a) - entirely full of current data;(2) PARTIALLY FULL (26b) - partially full of current data;(3) UNFORMATTED (26c) - empty; contains no data;(4) MASS DELETE (26d) - contains only obsolete data because of an unqualified deletion (mass delete) of data; or(5) QUALIFIED DELETE (26e) - contains only obsolete data because of a qualified deletion of data.When scanning over the data in a segment, UNFORMATTED and MASS DELETE pages are skipped. QUALIFIED DELETE pages are locked, and then skipped if they still contain only obsolete data when the lock is obtained.