Abstract: Requests to be executed in the database system are received, where a plurality of the requests are provided in a queue for later execution. Priority indicators are calculated for assignment to corresponding ones of the plurality of requests in the queue, where the priority indicators are calculated based on delay times and predefined priority levels of the requests. The requests in the queue are executed in order according to the calculated priority indicators.

Abstract: A database system includes an optimizer to generate resource estimates regarding execution of a request in the database system, and a regulator to monitor execution of a request and to adjust a priority level of the request based on the monitored execution and based on the resource estimates provided by the optimizer. The regulator is executable to further feed back statistics regarding execution of the request to the optimizer to improve accuracy of resource estimates provided by the optimizer.

Abstract: A computer-implemented method, apparatus and article of manufacture for optimizing a database query. A query execution plan is generated for the database query, which may be stored in an in-line query capture database. Execution of the query execution plan may be monitored in order to generate performance information, which also may be stored in the in-line query capture database. The data stored in in-line query capture database may be used during the initial generation of query execution plans, as well as for the re-optimization of a query execution plan, during the execution of the query execution plan.

Abstract: A filter receives a request to perform an operation in a database system, and the filter receives a resource estimate relating to the request from an optimizer. The filter determines whether the resource estimate exceeds an available resource of the database system, and if so, the filter rejects the request prior to execution of the request.

Abstract: A computer-implemented method, apparatus and article of manufacture for optimizing a database query. Resource usage of one or more resources of the computer system are monitored. A condition code representative of the monitored resource usage is stored. A cost model is modified using the stored condition code. A query execution plan is generated for the database query using the modified cost model. The query execution plan is then executed in order to retrieve data from a database stored on the computer system, wherein the retrieved data is presented to a user for subsequent use and analysis.

Abstract: For a given pool of database requests, a database system generates an integrated execution plan for multiple ones of the database requests in the pool. The database system determines whether to execute the integrated execution plan or individual execution plans corresponding to the respective multiple database queries. The determining is based on one or more criteria including performance goals corresponding to the respective multiple database requests.

Abstract: A method and system for eliminating unnecessary statistics collections for query optimization in a database stored on a computer. Statistics are unnecessary when a re-generated query execution plan that does not use the statistics is equivalent to an original query execution plan that uses the statistics. To determine this, an original query execution plan is created for each query in a specified workload using the statistics in the database. A search is performed of the statistics in order to enumerate one or more candidate sets of statistics to be eliminated. One or more of the candidate sets of statistics are removed from consideration prior to creating the re-generated query execution plan for each query in the specified workload.

Abstract: A computer-implemented method, apparatus and article of manufacture for optimizing execution of database queries in a computer system. In one embodiment, the steps and functions include: generating first and second query execution plans for first and second requests, wherein the first and second query execution plans are each comprised of one or more steps that scan a specified table in a database stored on the computer system in order to retrieve data from the table; and executing the first and second query execution plans, wherein intelligent query dispatching is performed on the steps of the first and second query execution plans to ensure that the steps share the data retrieved from the table and cached in memory.

Abstract: A database system has the ability to perform sampled statistics collection, in which collection of statistics of a table is based on a sample (less than all rows of the table). The sample size is adjusted as the table is scanned in response to detecting a predetermined characteristic of the table (e.g., skewed data values are detected).

Abstract: A method and system for managing indexes used to retrieve data from a database stored on a computer, includes determining whether any marginal indexes exist in the database, and removing one or more of the marginal indexes from the database. An index is considered marginal when: (1) it is an access path for one or more queries but the index's performance is matched or nearly matched by one or more other alternative access paths, and/or (2) its overhead has become a concern. These steps or functions are invoked by one or more statements or instructions that cause the computer to perform a Drop Index Analysis on a specified list of tables in the database for a specified workload. The Drop Index Analysis allows users to specify: (1) how many indexes to consider dropping, and/or (2) how much disk space that dropped indexes should free up.

Abstract: A computer-implemented method, apparatus and article of manufacture for optimizing a database query. Resource usage of one or more resources of the computer system are monitored. A condition code representative of the monitored resource usage is stored. A cost model is modified using the stored condition code. A query execution plan is generated for the database query using the modified cost model. The query execution plan is then executed in order to retrieve data from a database stored on the computer system, wherein the retrieved data is presented to a user for subsequent use and analysis.

Abstract: A method and system for eliminating unnecessary statistics collections for query optimization in a database stored on a computer. Statistics are unnecessary when a re-generated query execution plan that does not use the statistics is equivalent to an original query execution plan that uses the statistics. To determine this, an original query execution plan is created for each query in a specified workload using the statistics in the database. A search is performed of the statistics in order to enumerate one or more candidate sets of statistics to be eliminated. One or more of the candidate sets of statistics are removed from consideration prior to creating the re-generated query execution plan for each query in the specified workload.

Abstract: A computer-implemented apparatus, method, and article of manufacture for optimizing a database query. System conditions and operating environment events that occur during operation of the computer system are monitored. An n-dimensional optimizer matrix is used to identify at least one rule resulting from the monitored system conditions and operating environment events. An optimal query execution plan is selected from among a plurality of query execution plans generated for the query in response to the identified rule.

Abstract: A computer-implemented method, apparatus and article of manufacture for optimizing a database query. A query execution plan is generated for the database query, which may be stored in an in-line query capture database. Execution of the query execution plan may be monitored in order to generate performance information, which also may be stored in the in-line query capture database. The data stored in in-line query capture database may be used during the initial generation of query execution plans, as well as for the re-optimization of a query execution plan, during the execution of the query execution plan.

Abstract: A database system has the ability to perform sampled statistics collection, in which collection of statistics of a table is based on a sample (less than all rows of the table). The sample size is adjusted as the table is scanned in response to detecting a predetermined characteristic of the table (e.g., skewed data values are detected).