Validating multiple execution plans for database queries
AssigneeMicrosoft Corporation
InventorsCesar A. Galindo-Legaria, Florian Waas
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Abstract
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.
Claims5
A system for validating multiple alternative execution plans for a single database query, comprising:
- a search engine responsive to the query for constructing a data structure containing a plurality of groups each including a number of alternative operators, at least some of the operators having pointers to one or more different ones of the groups;
- a ranking module for ranking the operators in the groups and for unranking them so as to construct a plurality of different execution plans for the query, wherein each execution plan is assigned a unique global rank, based on operator rank data, that identifies one respective execution plan from all other possible execution plans;
- and
- a validation module for validating the execution plans from the ranking module.
Dependencies are inferred from the claim text.