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PENSION PLANS
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Technical Examples
- Validation of large numbers of alternative execution plans for a database query, either an exhaustive enumeration of the complete space of alternatives, or else an unbiased random sample, is performed by efficiently constructing execution trees from a data structure having groups alternative operators that are ranked in a directory. Each global rank of a plan identifies that plan uniquely among all the alternative plans. The operators are unranked from the directory according to a specification that characterizes the desired plans.
- Validation of large numbers of alternative execution plans for a database query, either an exhaustive enumeration of the complete space of alternatives, or else an unbiased random sample, is performed by efficiently constructing execution trees from a data structure having groups alternative operators that are ranked in a directory. Each global rank of a plan identifies that plan uniquely among all the alternative plans. The operators are unranked from the directory according to a specification that characterizes the desired plans.
- Database system query optimizers use several techniques such as histograms and sampling to estimate the result sizes of operators and sub-plans (operator trees) and the number of distinct values in their outputs. Instead of estimates, the invention uses the exact actual values of the result sizes and the number of distinct values in the outputs of sub-plans encountered by the optimizer. This is achieved by optimizing the query in phases. In each phase, newly encountered sub-plans are recorded for which result size and/or distinct value estimates are required. These sub-plans are executed at the end of the phase to determine their actual result sizes and the actual number of distinct values in their outputs. In subsequent phases, the optimizer uses these actual values when it encounters the same sub-plan again.
- Described herein are approaches for generating execution plans for database commands that include an in-list predicate. The approaches can be used to generate execution plans that exploit the power of in-list iterators in ways and under circumstances not previously supported by conventional DBMSs. An in-list iterator may be used with execution subplans for processing multi-column in-list queries. An in-list iterator is used with execution subplans that scan function-based indexes. The execution plans for a multi-column in-list query limit table scans to only table partitions that contain data that satisfy the query.
- The present invention provides a technique of assisting in forming plans of measures for management reforms, which are specific to an individual enterprise, and a technique of verifying formed plans of measures. In the present invention, a general business-operation-index vector f that includes a plurality of indexes indicating the condition of business management; a general plan-of-measures vector x including a plurality of plans of measures which are information about how to deal with the condition indicated by each index included in the general business-operation-index vector f; and a problem-index vector f', are used. On the basis of these, a problem-index-plan-of-measures matrix Mm' is produced which defines correlation between the problem-index vector f' and a plan-of-measures vector x' (Step 3221). A potential plan-of-measures vector x' is selected from the general plan-of-measures vector X by extracting the plans of measures in the column of the matrix Mm' (Step 3222). A gross-investment (necessary to execute plans of measures) matrix Mi is produced (Step 3223). A relational expression between the problem indexes and the plane-of-measures (f'=Mm'·x') are produced Step 3224).
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