摘要:
Database indexes include multiple fields that are used to track how the components of the index are used. An index component monitoring mechanism tracks how the components of the index are used, and updates fields in the index accordingly. Such component-level statistics allow a query optimizer to make more intelligent decisions regarding when to build a new index and when to discard an index, and also provide information regarding which queries are using the index, the maintenance cost of the index, and the selectivity of the index when used to process a query.
摘要:
An apparatus and method optimize a query in a computer database system having a DISTINCT specifier. An SQL SELECT statement with a DISTINCT specifier is analyzed to determine if the expression can be optimized, and if so, the SELECT statement is reformulated to improve system performance. In preferred embodiments, the query optimizer eliminates the DISTINCT specifier in the outer select statement to reformulate the query. In other preferred embodiments, a query optimizer reformulates the query before being sent to the database manager to optimize the query to improve system performance.
摘要:
A method, system, and computer program product that provide for more uniform pricing of utility computing resources, such as a computing grid. One aspect of the present invention is a method of calculating costs in a utility computing environment comprising receiving a request to process a work unit from a requester, generating at least one performance metric associated with the work unit, and debiting the requestor for processing the work unit based at least in part on the performance metric. The performance metric in this embodiment is related to an amount of resources required to process the work unit under predetermined conditions.
摘要:
A method, system and article of manufacture for query execution management in a data processing system and, more particularly, for managing execution of queries including user-defined functions. One embodiment provides a method for managing execution of a query against data of a database. The method includes receiving a query against the data of the database, the query having at least one query condition including a user-defined function. It is determined whether the user-defined function satisfies a predefined index applicability criterion. If the user-defined function satisfies the predefined index applicability criterion, an index over relevant data of the database is created for the user-defined function. The index is suitable for use in execution of the query against the data of the database to determine a corresponding query result.
摘要:
A database monitor tracks performance statistics and information about the execution of different SQL statements. In particular, the monitor tracks information about the individual instructions that comprise a complex query. The performance statistics and information from these individual elements provide insight into a query's performance and may show why a query's performance is below expectations.
摘要:
A computer-implemented method, system and computer product including a scheduling manager residing in memory; whereby the scheduling manager dynamically manages access of additional computer resources to be applied to work items of a program based on their valuations relative to the processing costs thereof.
摘要:
A system, method and article of manufacture for presentation of data on a display device and, more particularly, for managing presentation of data in a tabular form on a display device. One embodiment provides a method of managing display of requested data on a display device. The method comprises, in response to a request for data, receiving the requested data in a tabular form having a plurality of columns and rows ordered according to an initial order; re-ordering at least one of the columns and rows, wherein the re-ordering is done on the basis of rules configured to intelligently arrange presentation of the requested data to a user; and outputting the re-ordered requested data for display on the display device.
摘要:
A method, apparatus, system, and signal-bearing medium that in an embodiment replace an element in a query with a backup if the element is not available, but the backup is available. An element may also be removed from the query if the element is not required. In various embodiments, the element may be a table or a user-defined function. In this way, the query may still execute even if the element is not available.
摘要:
A method, apparatus, system, and signal-bearing medium that in an embodiment track a history of statements that query data from a database. When a new statement is received, the history is searched for a correlation between the new statement and previous statements. The correlation is based on host variables in the history and the new statement. When a correlation is found, a prediction is made for the next statement to be received based on the previous statement in the history for which the correlation was found. The prediction is then used to retrieve pages from the database into a cache, which may be used by a subsequent statement.
摘要:
Systems, methods, and articles of manufacture for improving the efficiency of executing a query are provided. Queries frequently issued in a primary processing environment (e.g., a primary logical partition) may be run in a background processing environment (e.g., a background logical partition) with different access plans to determine the access plan that results in the least execution time. For some embodiments, in an effort to avoid executing queries that may have an adverse system-wide impact, selected queries may be analyzed in the background processing environment prior to being executed. This analysis may be performed to ensure the execution time of the query will not exceed a specified threshold, and/or will not result in excessive contention when executed in the primary processing environment.