Abstract: A method and apparatus for online reorganization of a database which does not prevent a process from accessing the database during the data reorganization. The invention uses a non-blocking drain to lock on a database, unloads a copy of the data contained in the database, reorganizes the copied data, loads the reorganized data into a shadow location, applies log records to the shadow location data so that the reorganized data may be adjusted for any changes to the database after the data was copied and reorganized, and then replaces the data in the database with the reorganized data. The non-blocking drain does not prevent other requests on the database from being processed while the reorganization lock is in place, except briefly when the reorganized data replaces the data in the database.

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: 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: Disclosed is a system, method, and program for reorganizing at least one database object. The database object is comprised of at least one database file. Each database file has a name. Source database files including data for the database objects subject to the reorganization have source names. Shadow copies of the source database files are created and shadow names for the shadow copies are generated, such that the source names and corresponding shadow names are different. The data in the shadow copies is reorganized. After the reorganization, the shadow names are used to access the database files for the reorganized database objects.

Abstract: Castout processing for duplexed data structures. A selective data item is written from a primary instance of a data structure to at least one storage medium. A determination is made as to whether the selective data item can be deleted from a secondary instance of the data structure. If the selective data item can be deleted, it is deleted from the secondary instance.

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: 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: An integrated DBMS solution to recover primary site database based upon the maintenance of a shadow copy of the primary site's database data and logs at a remote site. Both the primary site DBMS and the remote site DBMS may support write-ahead logging protocol in which log records are written to a log data set before database updates are entered into the remote site storage. The remote site serves at least two functions: as a “tracker” DBMS and as a “take-over” DBMS. The tracker function maintains a shadow copy of the primary site's database data sets at the remote site. The multi-phased take-over function uses the shadow copies to update the remote site database data sets and substitutes them for primary site database data sets made unavailable by an unplanned disaster at the primary site.

Abstract: A method and apparatus for online reorganization of a database which does not prevent a process from accessing the database during the data reorganization. The invention uses a non-blocking drain to lock on a database, unloads a copy of the data contained in the database, reorganizes the copied data, loads the reorganized data into a shadow location, applies log records to the shadow location data so that the reorganized data may be adjusted for any changes to the database after the data was copied and reorganized, and then replaces the data in the database with the reorganized data. The non-blocking drain does not prevent other requests on the database from being processed while the reorganization lock is in place, except briefly when the reorganized data replaces the data in the database.

Abstract: Data is loaded to a data structure while an image copy of the data structure is concurrently formed. After data records are obtained from one or more data sources, each of the data records is associated with one of multiple pages. As each page is completed, it is written to a primary data structure. Also upon completion of each page in the primary data structure, concurrently with storage of the page in the primary data structure, an image copy of the page is made in an image copy data set. Partially or completely failed primary data structures may also be restored using image copies made according to the invention. Timestamps mark the time at which each page are made; image copy pages include the same timestamp as their respective primary pages. Upon detecting a data structure failure, each page of the image copy is sequentially reviewed. For each image page being reviewed, the page's timestamp is compared with the timestamp of the corresponding page from the primary data structure.

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 system and method for a computer system having a plurality of DBMS providing a coordinating and assisting function. If a DBMS performs a coordinating function, it is referred to as a coordinating DBMS. If a DBMS performs an assisting function, it is referred to as an assisting DBMS. Each coordinating DBMS receives a query from a user application, decomposes the query into multiple parallel tasks, and allocates the parallel tasks to all of the DBMSs in the system. Each assisting DBMS receives one or more parallel tasks from a coordinating DBMS, executes the parallel tasks and returns the results to the coordinating DBMS. The coordinating DBMSs and assisting DBMSs access one or more storage devices. Furthermore, the present invention comprises a system and method for dynamically disabling a parallel mode on the coordinating DBMSs and the assisting DBMSs.

Abstract: A system and method for a computer based system having one or more consuming DBMSs and one or more producing DBMSs such that the producing DBMSs produce workfiles for the consuming DBMSs. A producing DBMS uniquely identifies the bufferpool pages comprising a workfile, uniquely identifies the workfile, and flushes only the bufferpool pages corresponding to the workfile to a storage device. The producing DBMS further notifies the consuming DBMS that the workfile is available and receives a reply from the consuming DBMS indicating that the consuming device retrieved the data from the storage device. The consuming device receives notification from the producing DBMS, retrieves the workfile, and replies to the producing DBMS that it has retrieved the workfile.

Abstract: A resource allocation manager and technique for servers within a computer system. Resources are initially allocated to servers and in order to enhance system performance, resources are reallocated based on a minimization of the maximum performance index. In one example, the server with the largest performance index is allocated additional resources and the server with the smallest performance index loses some of its resources.

Abstract: Disk check bits refer to bit patterns stored in particular bytes of a page which are used to detect errors in writing the page to storage. Every time a page is obtained from storage, changed from the version retained in storage, and written back to storage, the check bit pattern on the changed page is altered to be different from the bit pattern on the storage page. This is because the changed page overwrites the stored page. The invention provides a method for managing the check bits in a multi-DBMS system employing a high-speed shared electronic store as a store-in cache for all pages obtained from disk storage. When a page is first obtained from disk storage by a DBMS and changed, check bit information for the page is maintained in a directory of the storing cache which indicates what the patterns are for the version of the page in the disk storage. All pages which are modified are stored in the store-in cache and are only returned to disk storage from the cache.