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: Provided are a method, system, and program for making data available to an application program. A cursor is generated positioned with respect to a result table, wherein the cursor specifies a search criteria, and wherein the result table includes rows from a base table that satisfy the search criteria. A fetch request is received indicating to position the cursor on a plurality of rows of the result table. The cursor is positioned on the plurality of rows of the result table indicated in the fetch request that satisfy the search criteria.

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: System, method, and program product for managing transactions on a plurality of Database Management Systems residing on separate participant servers and a coordinator server. A single transaction proceeds by multiple steps across more then one of the plurality of Database Management Systems as participants. Savepoints are assigned to the participants across the Database Management System, with at least one savepoint within a multiple step transaction. The DBMS responds to application requests to rollback to savepoint by rolling back the transaction, across the Database Management System participants, to the savepoint Further disclosed is a program product that contains code, which, either as written on the medium, or as instantiated in RAM, or both, controls the operation of a distributed database management system.

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: System, method, and program product for managing transactions on a plurality of Database Management Systems residing on separate participant servers and a coordinator server, A single transaction proceeds by multiple steps across more then one of the plurality of Database Management Systems as participants. Savepoints are assigned to the participants across the Database Management System, with at least one savepoint within a multiple step transaction. The DBMS responds to application requests to rollback to savepoint by rolling back the transaction, across the Database Management System participants, to the savepoint Further disclosed is a program product that contains code, which, either as written on the medium, or as instantiated in RAM, or both, controls the operation of a distributed database management system.

Abstract: A method, apparatus, and computer readable medium containing programming instructions for reducing lock contention of concurrent transactions is disclosed. 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. A lock is requested if the row satisfies the set of predicates, and the scan is suspended, if the requested lock is refused. The request is repeated and the row is re-evaluated when the lock is permitted. If thereafter the row still satisfies the set of predicates, the row is returned.

Abstract: A method is disclosed for deferring enforcement of referential constraints in large-scale data base operations such as the population or loading of relational tables 10, 12. First, the new rows are loaded in a Data Load phase 24 into the tables, and information on the new rows and their constraints is extracted and sorted 26 into a sorted key data set 68. Any primary indexes 22 required for constraint checking are then updated 28 using the sorted key data set. The new rows are then checked 70 for constraint violations, such violations are rectified 72 to restore the table's referential integrity, and a deletion data set 80 is produced. The deletion data set is merged and sorted 86 with row information 53 stored during loading, and the result is used to copy 88 the new rows violating referential constraints to a separate discard data set 48 where they can be corrected and reloaded into the table. Finally, an error summary report 36 is generated for use in correcting the discard data set.