Patent application number | Description | Published |
20090049012 | APPARATUS, SYSTEM, AND METHOD FOR ENSURING QUERY EXECUTION PLAN STABILITY IN A DATABASE MANAGEMENT SYSTEM - An apparatus, system, and method are disclosed for ensuring query execution plan stability in a database management system. The present invention binds a static database query to a new query execution plan (QEP) that produces the same result set as an original QEP bound to the static database query. Next, the present invention identifies one of the original QEP and the new QEP as a primary QEP and automatically collects execution statistics for the original QEP and the new QEP. Finally, the present invention automatically selects one of the original QEP and the new QEP as the primary QEP in response to completion of the automatic collection of execution statistics, the primary QEP selected such that the automatically selected QEP provides optimal execution performance based on performance criteria in comparison to the automatically unselected QEP, the primary QEP selected based on the execution statistics. | 02-19-2009 |
20090063397 | METHOD AND SYSTEM FOR DISJUNCTIVE SINGLE INDEX ACCESS - A method for performing disjunctive single-index access on a database is disclosed. The method includes a query engine determining whether a first OR predicate and a second OR predicate map to a shared index. Responsive to the query engine determining that the first OR predicate and the second OR predicate map to the shared index, the first OR predicate and the second OR predicate are ordered in an ascending sequence. A first range of the first OR predicate is queued. A first row of the shared index is probed for the first range of the first OR predicate. Whether the first row is disqualified by the first OR predicate is determined. Responsive to determining that the first row is not disqualified by the first OR predicate, the row is reported in a result reporting structure. Responsive to determining that the row is disqualified by the first OR predicate, whether the first range of the first OR predicate overlaps a second range of the second OR predicate is determined, and, responsive to determining that the first range of the first OR predicate overlaps the second range of the second OR predicate, the row is checked against second range of the second or predicate. | 03-05-2009 |
20100114868 | QUERY EXECUTION PLAN EFFICIENCY IN A DATABASE MANAGEMENT SYSTEM - An apparatus, system, and method are disclosed for improving query execution plan efficiency in a database management system. The present invention binds both static database queries and dynamic database queries to new query execution plans (QEPs) that produce the same result set as a former QEP bound to the database queries. Next, the present invention identifies one of the former QEPs and the new QEP as an active QEP and automatically collects execution statistics for one of the former QEPs and the new QEP. Finally, the present invention automatically selects one of the former QEPs and the new QEP as the active QEP in response to completion of the automatic collection of execution statistics, the active QEP selected such that the automatically selected QEP provides optimal execution performance based on performance criteria in comparison to the automatically unselected QEP, the active QEP selected based on the execution statistics. | 05-06-2010 |
Patent application number | Description | Published |
20130159321 | METHOD AND APPARATUS FOR OPTIMIZING ACCESS PATH IN DATABASE - Apparatuses and methods for optimizing access path are provided. Execution of a query statement is sampled to obtain the information about a plurality of executing instances, the information about each executing instance comprises the literal value of the query statement in the instance and the filter factor corresponding to the literal value. The plurality of instances are grouped into a plurality of groups based on the filter factors corresponding to the literal values. The average filter factor of each group and the occurrence frequency of the group are obtained. The candidate access path created for the average filter factor of each group is accordingly obtained, and by taking the occurrence frequencies as weights, the weighted execution cost of each candidate access path is calculated for each group. The candidate access path with the minimum sum of the weighted execution costs for all groups is determined as the optimal access path. | 06-20-2013 |
20130262435 | ADAPTIVE QUERY EXECUTION PLAN ENHANCEMENT - An adaptive query execution plan enhancement is provided by: selecting a sample of literal sets from an execution history of a query statement; determining a plurality of access paths by applying each literal set in the sample to the query statement; for each given access path of the plurality of access paths, determining a total execution cost by applying each literal set in the sample to the given access path; and selecting a preferred access path from the plurality of access paths based on the total execution costs for each given access path. A plurality of preferred access paths for a plurality of query statements in an application workload is collected and may be presented as a query execution plan enhancement recommendation to users. | 10-03-2013 |
20140108378 | TECHNIQUE FOR FACTORING UNCERTAINTY INTO COST-BASED QUERY OPTIMIZATION - A technique for factoring uncertainty into cost-based query optimization includes: determining the degree of uncertainty involved in the cost estimates for the query, determining the degree of sensitivity the query has to that uncertainty, and determining if there is an access path that performs well across the range of possible conditions that could occur at execution time, reducing the risk of performance spikes and performance volatility. If such an access path exists, select that access path; if not, perform parametric query optimization or query re-optimization. | 04-17-2014 |
20140214797 | TECHNIQUE FOR FACTORING UNCERTAINTY INTO COST-BASED QUERY OPTIMIZATION - A technique for factoring uncertainty into cost-based query optimization includes: determining the degree of uncertainty involved in the cost estimates for the query, determining the degree of sensitivity the query has to that uncertainty, and determining if there is an access path that performs well across the range of possible conditions that could occur at execution time, reducing the risk of performance spikes and performance volatility. If such an access path exists, select that access path; if not, perform parametric query optimization or query re-optimization. | 07-31-2014 |