摘要:
In an embodiment, a query tree is created that represents a query expression, where the query tree includes a union of nodes. Each of the nodes represents a respective partition of a table, and the query expression specifies a key value and the table. A determination is made whether a result set exists that includes the key value, where the result set was previously retrieved from the table. If the determination is true, a decision is made based on the result set whether the key value is stored in the respective partition represented by each of the nodes. The nodes for which the key value is not stored in the respective partition are removed from the query tree to create an optimization tree, and the optimization tree is used to retrieve data from the table. In this way, nodes that are not necessary to be searched may be removed from query trees, in order to increase the performance of the query.
摘要:
A method, system and article of manufacture for migration of databases and, more particularly, for optimizing migration of a database from a source system to a target system. One embodiment provides a computer-implemented method for optimizing migration of a database from a source system to a target system. The method comprises collecting source parameters related to performance characteristics for the database on the source system. On the basis of the collected source parameters and target parameters of the target system database configuration information is generated. The target parameters will affect the operation of the database on the target system as compared to the operation of the database on the source system. The database configuration information is applicable to tune the database to operate on the target system. The method further comprises configuring the database to run on the target system according to the database configuration information.
摘要:
In a partitioned database system that includes multiple logical partitions, query performance is estimated with a current allocation of resources. A determination is made whether additional resources are available or whether resources could be reallocated from one logical partition to a different logical partition. Query performance is then estimated again with a proposed reallocation of resources. This process continues iteratively until an allocation of resources is determined that will enhance the performance of the query. A resource allocation mechanism then initiates the reallocation of resources. In this manner, resources in logical partitions may be dynamically and autonomically reallocated to improve the performance of a query to a partitioned database.
摘要:
The activity of a database is monitored, and index split options are dynamically determined from the monitored database activity. Appropriate action may then be taken based on the dynamically determined index split options. For example, the index may be automatically split using the dynamically determined index split options. A user command that specifies index split options may be compared to the dynamically determined index split options, and if the user command is not compatible with the dynamically determined index split options, the command may be inhibited, or the user may receive a warning message in response to the command. In addition, existing index use may be monitored, and if the monitored index use indicates the index is split poorly, the index may be re-generated using the dynamically determined index split options.
摘要:
A database optimizer collects statistics regarding applications accessing a database, and makes one or more changes to the database schema to optimize performance according to the collected statistics. In a first embodiment, the optimizer detects when a certain type of application accesses the database a percentage of time that exceeds a predefined threshold level, and if the data in the database is stored in a less-than-optimal format for the application, the data type of one or more columns in the database is changed to a more optimal format for the application. In a second embodiment, the optimizer detects when one type of application accesses a column a percentage of time that exceeds a first predefined threshold level and is less than a second predefined threshold level, and creates a new column in the database so the data is present in both formats.
摘要:
Methods, articles of manufacture and systems for managing Web services. One embodiment provides a method comprising providing one or more rules configured to determine whether a Web service is deterministic. A deterministic Web service produces in subsequent executions identical output in response to identical input. The one or more rules are associated with the Web service.
摘要:
An apparatus, program product and method utilize one or more usage statistics, which are reflective of what data is actually and/or likely to be used by a client when processing a database query, to reduce or eliminate the transfer of unnecessary data between a client and server in a client-server database management system. Information such as the columns that are or have been used and/or the number of rows that have been accessed, may be utilized to identify certain data that is likely to not be used during processing of the database query. Based upon the data that has been identified, a subset of the data that would otherwise be returned as a result of the database query may be identified and returned to a client, often substantially reducing the amount of data required to be retrieved by a client in connection with a database query.
摘要:
A method, apparatus, system, and signal-bearing medium that in an embodiment determine whether a task is allowed to use a service-enabled resource, wherein the service-enabled resource is disabled until a fee is paid. If the task is allowed to use the service-enabled resource, then the service-enabled resource is allocated to the task. If the task is not allowed to use the service-enabled resource, then a non-service enabled resource is allocated to the task.
摘要:
Methods, systems, and computer program products for dynamically adjusting computer resources, as appropriate, in response to predictions of batch runtimes as well as for rendering costs of the computer resources actually utilized, which costs are consistent with customer demands.
摘要:
Methods, systems, and computer program products for dynamically adjusting computer resources, as appropriate, in response to predictions of query runtimes as well as for rendering costs of the computer resources actually utilized, which costs are consistent with consumer demands.