Abstract: An apparatus and method to optimize a query access plan in a computer database system. In preferred embodiments, the query optimizer determines the query can be optimized and generates for the query an optimized access plan that eliminates records defined by a Where clause and one or more ordering criteria prior to ordering the records (sorting or grouping) and then returning a first n rows.

Abstract: A database engine and optimizer framework support the use of transitive closure to assist in rewriting GROUP BY and ORDER BY clauses to reduce the number of referenced tables (optimally to a single table if possible) and to free the join order selected for the query plan. The SQL parser and optimizer, by performing transitive closure on the selection, or search, conditions is able to identify which fields referenced by the ORDER BY and GROUP BY clauses can be replaced with equivalent fields to improve the performance of the query. In one instance, the fields are replaced so that the ORDER BY or GROUP BY clause references only a single table. If more than one such possible ORDER BY or GROUP BY clause exists, then the optimizer selects from among the different possible clauses to select the one that provides the best performing join order.

Abstract: A query plan modification system and method relate to a database system that includes a cost-based optimizer for generating access plans. The database system also permits a user to view an access plan that has been generated by a particular SQL query and modify the access plan if desired. The user specifies customizations that are associated with the access plan so that when that plan is executed, the customizations are executed as well. Exemplary customizations include specifying an initialization file specific to a query, specifying different implementation methods than those in the original access plan, prohibiting rebuilding of an access plan, and over-riding or ignoring a clause within the query that is used to generate the access plan.

Abstract: The invention, in an embodiment, relates to optimizing database performance by taking advantage of sleepy drives. The invention analyzes queries to indexes based on usage frequency, and determines whether to access an index stored on a sleepy drive, or perform an alternate access plan based on green optimization. Furthermore, the invention transfers data, such as, for example, indexes, files, data areas, journals, and statistics, between active and sleepy drives based on usage frequency. In another embodiment, the invention provides an improved sleepy drive which optimizes energy savings by a graduated degree based on a speed setting. In yet another embodiment, the invention controls when read-write heads are unloaded from disks to reduce drag and power consumption by a disk drive.

Abstract: A query plan modification system and method relate to a database system that includes a cost-based optimizer for generating access plans. The database system also permits a user to view an access plan that has been generated by a particular SQL query and modify the access plan if desired. The user specifies customizations that are associated with the access plan so that when that plan is executed, the customizations are executed as well. Exemplary customizations include specifying an initialization file specific to a query, specifying different implementation methods than those in the original access plan, prohibiting rebuilding of an access plan, and over-riding or ignoring a clause within the query that is used to generate the access plan.

Abstract: An apparatus and method to optimize a query access plan in a computer database system. In preferred embodiments, the query optimizer determines the query can be optimized and generates for the query an optimized access plan that eliminates records defined by a Where clause and one or more ordering criteria prior to ordering the records (sorting or grouping) and then returning a first n rows.

Abstract: A method, apparatus, and program product select a pre-started job from among a plurality of pre-started jobs in which to perform a task in a computer system with a NUMA configuration. An attempt to perform a task is received as a connection. Information associated with the connection is compared to information associated with a plurality of pre-started jobs. In response to comparing the information, it is determined either that a pre-started job was previously used to perform the task or that no pre-started job was previously used to perform the task. In response to either determination, another pre-started job is determined in which to perform the task. The other pre-started job is determined based on affinity with the task, and may be reallocated to perform the task.

Abstract: A method, apparatus, and program product utilize intelligent job functionality to diagnose an error in a computer. After detecting an error in a first job processing a task, and in response to another attempt to perform the task, a job selection algorithm selects a predetermined job in which to perform the task and diagnose the error. The predetermined job can be the first job or a new job associated with a signature that corresponds to the task that experienced the error. The predetermined job can be used to diagnose the error in a debugging session. Alternately, the first job may enter a debug session immediately after experiencing an error.

Abstract: An apparatus and program product determine information indicative of a performance differential between operation of a computer with the standby resource activated and operation of the computer with the standby resource inactivated. The information is communicated to a user. The standby resource may be activated in response to the determination.

Abstract: An apparatus, program product and method that employ a dynamic use of Look Ahead Predicate Generation that will enable the database, database engine, and/or query optimizer to alter the processing of a query, and react to sub-optimal access plan selection and additional factors arising after processing has begun, to heal many poor performing queries. Conventional use of LPG requires the query optimizer to decide whether or not to use LPG before the processing of a query begins. As a result, the query optimizer may not only make sub-optimal decisions, but the query optimizer may not consider additional factors that may arise as the query is processing. However, the dynamic use of LPG allows predicates to be built after processing of the query has started and the ability to alter the query's processing to improve query performance.

Abstract: An apparatus and program product that utilize at least one prematurely terminated processing of a database query to improve the processing of the database query. Due to the difficulty of conventional techniques to improve the execution and/or performance of long processing queries, (e.g., advanced user knowledge, assistance from an expert, etc.), users typically terminate long processing queries. As a result, long processing queries may not be improved, and because of the limited options, users may continue to prematurely terminate long processing queries. However, information related to the premature terminations of a database query may be utilized by a DBMS to generate and/or implement suggestions to improve the processing of the database query, resulting in improved query processing, improved performance, fewer premature terminations, and more satisfied users.

Abstract: Embodiments of the invention provide techniques for generating statistics for optimizing database queries containing user-defined functions (UDFs). In general, the statistics may be generated based on output values produced during past executions of a UDF. The statistics may also be generated based on input values received during past executions of the UDF. Additionally, the statistics may include input and output value pairs, such that a UDF output may be determined based on a UDF input. The generated statistics may be used by a query optimizer to determine an efficient query plan for executing the database query.

Abstract: Embodiments of the invention provide techniques for generating statistics for optimizing database queries containing user-defined functions (UDFs). In general, the statistics may be generated based on output values produced during past executions of a UDF. The statistics may also be generated based on input values received during past executions of the UDF. Additionally, the statistics may include input and output value pairs, such that a UDF output may be determined based on a UDF input. The generated statistics may be used by a query optimizer to determine an efficient query plan for executing the database query.

Abstract: Methods, systems, and computer program products are provided for improving the processing of database queries. Some embodiments include detecting an overly long running query execution plan, stopping execution of the plan, and utilizing the query optimizer to select an alternate plan for execution. Embodiments may utilize system timers which are set with a time limit for the first selected plan, with instructions to re-optimize and initiate selection of an alternate plan when the timer times out. Risky constructs may be located in the first plan and removed from future consideration for executing the query. In some embodiments, the additional overhead for non-problem queries consists of little more than creating and sending a message or setting a timer when starting query execution, and canceling a timer upon successful query processing completion. A secondary thread may be created responsive to detecting a long running query, to supervise selecting an alternate execution plan.

Abstract: Embodiments of the invention provide techniques for generating predicted cardinality statistics for grouped aggregation functions included in database queries. In general, characteristics of a database query are determined, and are then supplied to a probability function configured to generate a predicted cardinality statistic. The generated statistic represents a prediction of the probable cardinality of the results of a grouped aggregation function in the event that the query is executed. The predicted cardinality statistic may be used by a query optimizer to determine an efficient query plan for executing the database query.

Abstract: A computer system that, in an embodiment, receives a close command directed to a window, and determines whether the close command was received within a close threshold time of the display of the window. If the close command was received within the threshold time, in various embodiments, a close dialog is displayed, the window is faded, the window is shrunk, or a status message is displayed indicating that the window is closing. If a cancel command is received within a cancel-close threshold, the closing of the window is canceled. If the number of times the cancel command has been received for the window exceeds a cancel threshold, then in various embodiments, the close threshold is increased, magnification is recommended, a sound option is recommended, or speech recognition is recommended.

Abstract: Embodiments of the invention provide techniques for generating predicted cardinality statistics for grouped aggregation functions included in database queries. In general, characteristics of a database query are determined, and are then supplied to a probability function configured to generate a predicted cardinality statistic. The generated statistic represents a prediction of the probable cardinality of the results of a grouped aggregation function in the event that the query is executed. The predicted cardinality statistic may be used by a query optimizer to determine an efficient query plan for executing the database query.

Abstract: An apparatus, method and program product determines information indicative of a performance differential between operation of a computer with the standby resource activated and operation of the computer with the standby resource inactivated. The information is communicated to a user. The standby resource may be activated in response to the determination.

Abstract: Methods that utilize at least one prematurely terminated processing of a database query to improve the processing of the database query. The embodiments discussed track termination information associated with at least one user initiated premature termination of processing of a database query to improve the processing of the database query. Information related to the premature terminations of a database query may be utilized by a DBMS to generate and/or implement suggestions to improve the processing of the database query, resulting in improved query processing, improved performance, fewer premature terminations, and more satisfied users.

Abstract: In an embodiment, a problem record associated with a query is saved to a log if the query encountered a problem. The amount of data in the record is increased if an access plan associated with the query has changed within a threshold amount of time and decreased if the access plan has not changed. In various embodiments, the problem is that the query executes longer than a historical average for the query, the query executes longer than a threshold, or the query encounters a functional error. In an embodiment, a benchmark record is also saved to the log, the problem record is compared to the benchmark record, and the difference is presented. In various embodiments, an oldest record is periodically removed from the log, or an oldest record is removed from the log if the associated query has more than a threshold number of records.