Abstract: A computer apparatus and related method to reduce database congestion is provided. In one aspect, the computer apparatus and method may generate a new partition within a hierarchical data structure of interlinked nodes, if a distribution of key values stored in the hierarchical data structure is skewed in favor of a range of key values.

Abstract: In one implementation, a data store page recovery process includes selecting a page reference and an update record reference at a page recovery mapping based on a page identifier, accessing a backup page via the page reference, accessing an update record via the update record reference, and modifying the backup page according to the update record. The page reference is associated with the update record reference at the page recovery mapping.

Abstract: A merge optimization system to optimize a run merge process for runs including keys from a data source. The system may include a run generation module to generate a run of the keys in a predetermined order. The system may further include a key characterization module to characterize a distribution of the keys across the run at run generation time, and a run merge module executed by a computer system to selectively associate the runs based on the characterization.

Abstract: A computer executed method of exploiting correlations between original and desired data sequences during run generation comprises, with a processor, adding a number of data values from a data source to a first memory device, the first memory device defining a workspace, determining whether the data values within the workspace should be output in ascending or descending order for a number of runs, and writing a number of the data values as a run to a second memory device in the determined order.

Abstract: Computer-implemented systems and associated operating methods use performance maps created by evaluating robustness of a database operator, query plan, or query to analyze health of a currently-executing query. The computer-implemented system comprises logic that receives one or more robustness maps of measured database system performance acquired during database execution in a predetermined range of runtime conditions. The logic analyzes state of a currently-executing query by locating the query's performance on the robustness maps.

Abstract: There is provided a method for generating results for a sort operation. The method includes writing a subset of input to memory. The subset may be sorted based on the sort operation. The sorted subset may be compared to previous results. The previous results may be recalled from a client of the sort operation based on the comparison.

Abstract: An embodiment includes determining user loads and control parameter values. The determining control parameter values are mapped to a performance metric using a function. A constant performance metric is determined where the value of the function calculated at each control parameter value is less than said constant performance metric. An isocontour is defined based on the constant performance metric for each user load. Finally an operating envelope is calculated by correlating the isocontours of multiple user loads.

Abstract: A method of performing a database join is provided herein. The method includes receiving a query. The query may specify a join of a first table and a second table. The method further includes determining a new predicate based on a mapping between a first column of the first table and a second column of the second table for a plurality of tuples of the join. Further, the method includes modifying the query such that the query comprises the new predicate.

Abstract: Whether a change in workload of a database system has occurred can be determined. Investigative queries are formulated. Each investigative query is adapted to test a different resource or a different combination of resources of the database system. The investigative queries are run when the database system is in an unloaded state to acquire unloaded performance metrics. The investigative queries are run when the database system is in a loaded state to acquire loaded performance metrics. Whether executing a current workload of the database system, using a current configuration of the database system, will likely result in a problem developing at a later point in time can also be determined. Simultaneously with actual execution of the current workload on the database system using the current configuration, a simulation of execution of the current workload using the current configuration is performed. The simulation is performed more quickly than the actual execution.

Abstract: The disclosed embodiments relate to a system and method of applying policies. The method may include identifying a first entity and a first relationship, the first relationship defining an attribute related to the first entity. Additionally, the method may include identifying a policy associated with the first entity and the first relationship and applying semantics to determine a degree of relatedness between the first entity and a second entity. Further, the method may include applying the policy to a second relationship that defines an attribute related to the second entity if the degree of relatedness between the entity and the second entity is within a range of values.

Abstract: A method of managing the execution of a workload of transactions of different transaction types on a computer system. Each transaction type may have a different resource requirement. The method may include intermittently, during execution of the workload, determining the performance of each transaction type. A determination may be made of whether if there is an overloaded transaction type in which performance is degraded with an increase in the number of transactions of the transaction type. If there is an overloaded transaction type, the number of transactions of at least one transaction type may be changed.

Abstract: A method of determining a multiprogramming level (MPL) for a first computer subsystem may be implemented on a second computer subsystem. The method may include selecting an initial MPL interval having endpoints that bound a local extremum of a computer-system operation variable that is a unimodal function of the MPL. For each interval having a length more than a threshold, operation-variable values for two intermediate MPLs in the interval may be determined. The interval may be diminished by the section of the interval between the one of the intermediate MPLs having an operation-variable value further from the extremum, and the interval endpoint adjacent to the one intermediate MPL. The operating MPL may be set equal to the other intermediate MPL when the interval has a length that is not more than the threshold.

Abstract: A method of producing a representation of the progress of a process being performed on a database may be embodied in a data processing system. The method may include obtaining for each of a plurality of subprocesses included in the database process an estimated rate of using a system resource during execution of the subprocess and an estimated volume of data to be processed. The actual rate of using the first system resource and the actual volume of data processed during execution of the at least one subprocess may be determined for at least one of the plurality of subprocesses. An output signal may be generated that is representative of the estimated and actual rates and the estimated and actual volumes of data for the at least one subprocess.

Abstract: Whether a change in workload of a database system has occurred can be determined. Investigative queries are formulated. Each investigative query is adapted to test a different resource or a different combination of resources of the database system. The investigative queries are run when the database system is in an unloaded state to acquire unloaded performance metrics. The investigative queries are run when the database system is in a loaded state to acquire loaded performance metrics. Whether executing a current workload of the database system, using a current configuration of the database system, will likely result in a problem developing at a later point in time can also be determined. Simultaneously with actual execution of the current workload on the database system using the current configuration, a simulation of execution of the current workload using the current configuration is performed. The simulation is performed more quickly than the actual execution.

Abstract: A database query is submitted to a first query optimizer to receive a first query plan from the first query optimizer. The first query plan is set as a current query plan. As an entry point, the current query plan is executed against the database within a given environment of the database. Where execution of the current query plan within the given environment is problematic, the execution of the current query plan is prematurely terminated, and the database query is submitted to a second query optimizer. Where a second query plan that is different than any previous query plan for the database query has been received from the second query optimizer, the second query plan is set as the current query plan, and a risk to the database in executing the current query plan is determined. Where the risk is less than a threshold, the entry point is proceeded to.

Abstract: A data processing system performs query progress estimation based on processed value packets. In the illustrative data processing system, a database query processor comprises a query optimizer that creates a query plan, and a database plan executor that executes the query plan and observes intermediate result streams processed as the query plan is executed. A value packet manager anticipates value packets during query optimization, creates value packets as the intermediate result streams are processed, and compares anticipated value packets with created value packets to determine accuracy of the anticipated value packets and estimate query progress.

Abstract: Provided are, among other things, systems, methods and techniques for processing database queries, such as the following. A current database query to be executed is obtained, and a plan for executing the current database query is generated. A cluster that includes at least one previously executed database query is identified, based on similarity of the plan for executing the current database query to execution-plan information representing the cluster. Then, a query-execution characteristic is assigned to the current database query based on corresponding characteristic information representing the cluster, and performance of the current database query is managed based on the query-execution characteristic.

Abstract: A data processing system includes a query progress analyzer. The database processing system comprises a receiver that receives database queries including a target query directed to a database and a query analyzer. The query analyzer is coupled to the receiver and analyzes progress status of the target query based on comparison of measured target query resource usage to resource usage predicted from a query plan of the target query and measured system resource usage.

Abstract: Computer-implemented systems and associated operating methods create and use an operator map to identify and evaluate database query plan robustness landmarks. The computer-implemented system comprises logic that creates a map evaluating performance of an implementation of a database engine operator during execution under actual operating conditions. The logic measures and maps performance for a selected range of runtime conditions including resource availability and data characteristics.

Abstract: Computer-implemented systems and associated operating methods take measurements and landmarks associated with robustness maps and perform tests evaluating the robustness of a database engine's operator implementations and/or query components. The illustrative computer-implemented system comprises logic that receives one or more robustness maps of measured database system performance acquired during database execution in a predetermined range of runtime conditions and uses information from the robustness map or maps to prioritize potential changes that improve robustness of a database system implementation wherein landmarks in the robustness map or maps are operated upon as a robustness bug describing conditions under which a predetermined implementation of a database operator or query component degrades in a manner different from a predetermined expected manner.