Abstract: A method for retrieving information from a database includes identifying a cylinder. The cylinder includes a plurality of data segments. The method also includes retrieving the plurality of data segments from the cylinder during a single retrieval operation. In addition, the method includes storing the plurality of data segments in a cache.

Abstract: A method, computer program, and database system for configuring a model of a database system are disclosed. The database system has a configuration. Two or more ordered levels of configuration assistance are provided. Each of the levels offers a different combination of the following forms of assistance: no assistance, workload analysis, cost-based performance analysis, and simulation.

Abstract: A method and system for performing logical partial declustering in a shared-nothing database environment. The solution defines a partial declustering technique that can be used to dynamically adapt the declustering of base tables or intermediate result sets. The partial declustering technique is defined to limit the number of partitions (P) involved in an operation. The technique is defined to limit the operation to a subset of the system partitioning map (SPM). There are two components: the association between the data values and partitions is altered by restricting the data values to P? partition values where P? is less than P; and the actual partitions of the SPM selected are then derived based on a seed derived from a dynamic parameter, such as a session number, or a static parameter, such as a table identifier. In the case of intermediate result sets the number of P? partitions selected is a cost based decision based on the estimated number of rows in the input intermediate result sets.

Abstract: A method, computer system, and database system for optimizing processing of a request are disclosed. The request has one or more predicates. A list of the one or more predicates in the request is created and predicates for which an actual cost has not been stored or for which a cost cannot be estimated are pruned from the list. An access path for the each of the predicates is selected. The request is processed using the selected access paths producing one or more actual predicate costs. The one or more actual predicate costs are stored.

Abstract: FIG. 1 illustrates a database system 1 including a storage device 2. Device 2 stores table data 3 indicative of a plurality of rows 4. A source access module 5 is assigned to access one of rows 4, this particular row being designated by reference numeral 6. Module 5 is responsive to a command 7 for reading row 6 from device 2. Subsequently, module 5 writes row 6 to device 2 in a packet accessible by a target module 8, this packet presently taking the form of a shared spool file 9.

Abstract: There is provided a database system 1 including a source cluster, in the form of a source clique 2, for providing a clique shared spool file 3. This spool file is provided for consumption by a target module 4 belonging to a target cluster, in the form of a target clique 5. A node interconnect 6 receives of spool 3, and exports the spool for consumption by module 4.

Abstract: There is provided a parallel database system 1. System 1 includes a storage device 2 for maintaining a plurality of rows 3. System 1 also includes a plurality of access modules 4 for accessing in parallel a respectively assigned one or more of rows 3. An interface 5 receives data 6 indicative of a table 7 defined by a selection 8 of rows 3. A processor 9 is responsive to data 6 for selectively designating table 7 to be a single-module table. In this single module table, selection 8 is collectively assigned to an owning one of modules 4, indicated by reference numeral 10.

Abstract: A closed-loop supportability system for a database system includes a system health check administrator to allow the definition of supportability service level goals, a supportability regulator to regulate the execution of the database system to attempt to achieve the supportability service level goals, a supportability monitor to provide real-time views of the database system performance against the supportability rules, and a supportability correlator to provide analysis of the database system performance against the supportability rules.

Abstract: An optimization technique involves optimizing a SQL query, in which the SQL query includes a large IN-List query to access data in a table. The technique includes determining whether an IN-List exceeds a predetermined size, and, if so, removing the IN-List query statement and inserting a new query statement including a join operation.

Abstract: A method, computer system, and database system for automating a business rule in a database are disclosed. One or more database triggers associated with a business rule state machine are enabled and the business rule state machine is initialized.

Abstract: A method, computer program, and database system are disclosed for identifying a second source of a request sent to a database management system by a first source. A database message is received from the first source. The database message includes a second value for a second source-identifying parameter. The second value identifies a second source. The second value for the second source-identifying parameter is stored in a log.

Abstract: A database query is optimized for a star database schema that includes at least one fact table and at least one dimension table, where the database query includes an IN-List condition. During optimization, the IN-List is transformed into a relation and the relation is joined with the dimension table to produce a join result. The join result is then joined to the fact table.

Abstract: A method for retrieving information from a database includes identifying a cylinder. The cylinder includes a plurality of data segments. The method also includes retrieving the plurality of data segments from the cylinder during a single retrieval operation. In addition, the method includes storing the plurality of data segments in a cache.

Abstract: A method, database system and computer program are disclosed for optimizing a SQL query, in which the SQL query includes an IN-List. The method includes utilizing an array insert to insert the IN-List into a spool and piggybacking IN-List rows into a join step.

Abstract: A method, database system and computer program are disclosed for optimizing a SQL query, in which the SQL query includes an IN-List. An evaluation is performed to determine whether the IN-List query can be performed as a join operation. If so, a new access path that converting IN-List to a relation, and subsequently joined with the table to complete the IN-List query is cost and competes with other access paths.

Abstract: A technique for retrieving from a database system data stored in one or more tables is useful in performing cost based query rewrite on user database queries. The technique involves receiving a database query having at least two input relations and evaluating the domain size of the join column(s) of at least one of the input relations. If the domain size of the join column(s) of at least one evaluated input relation is relatively small, the method replaces the input relation(s) in the query with one or more constant expressions. The method also includes evaluating the query and delivering the selected data to the user.

Abstract: A technique for use in managing a data cache involves receiving one or more data objects to be written to a storage device. A temperature value is assigned to the one or more data objects before storing the data objects in the data cache. The temperature value assigned to the one or more data objects is compared with a threshold value. A copy of the one or more data objects is stored in the data cache if the assigned temperature value exceeds the threshold value.

Abstract: A synchronization method and apparatus defines event objects to enable synchronization of execution entities (e.g., threads). In one arrangement, the synchronization method and apparatus is used in conjunction with a Unix operating system. By defining event objects on which threads or other execution entities can wait upon, multiple threads can wait on one event, or alternatively, one thread can wait on multiple events. Furthermore, using the event-based synchronization method and apparatus, it is possible to specify behavior, particularly when one thread or other execution entity waits on multiple events. For example, the behavior specified can be that a condition is satisfied if any of the events occur, if all of the events occur, or some other logical combination of events occur.

Abstract: A method, computer program and database system are disclosed for joining a plurality of tables T1 through TN, where each of the tables has an associated Star Map, S1 through SN, respectively. Each Star Map includes bitmap entries having locations indexed by the hash of one or more values associated with one or more join key columns of its associated table. A bitmap entry in a Star Map, if set, indicates the presence of a row in its associated table that has entries in the one or more join key columns that together hash to the location of the bitmap entry. The method includes a) performing a Boolean operation using the bitmap entries of the Star Maps S1 through SN to produce a join Star Map SJ, b) using SJ to select rows from the tables T1 through TN, and c) joining the resulting rows to produce a join result.

Abstract: The described technique is for use in analyzing performance of a database system as it executes requests that are sorted into multiple workload groups, where each workload group has an associated level of service that is desired from the database system. The technique involves gathering data that describes performance metrics for the database system as it executes the requests in at least one of the workload groups, organizing the data in a format that shows changes in the performance metrics over time, and delivering the data in this format for viewing by a human user.