Home
PENCILS PLANS
Technical Examples
- An optical component (10a) for at least two pencils (4, 5) of rays has at least one one-piece element (1, 2) of inorganic optical material and at least two segments (6, 7) which are coordinated with the pencils of rays and of which the first segment (6) is substantially surrounded by the at least one second segment (7). According to the invention, a depression (8a) is provided between the first and the at least one second segment (6 and 7), respectively. This is formed in such a way that the first segment (6) is substantially optically shielded from the at least one second segment (7) and is held by means of at least one material bridge from the second segment with a stable attitude thereto.
- 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.
Thank you for using Findownersearch.com. If you have any comments or suggestions, please contact us.