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Method and apparatus for dynamically associating different query execution strategies with selective portions of a database table
Method and apparatus for dynamically associating different query execution strategies with selective portions of a database table
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机译:用于将不同查询执行策略与数据库表的选择性部分动态关联的方法和装置
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摘要
A query facility for database queries dynamically determines whether selective portions of a database table are likely to benefit from separate query execution strategies, and constructs an appropriate separate execution strategies accordingly. Preferably, the database contains at least one relatively large table comprising multiple partitions, each sharing the definitional structure of the table and containing a different respective discrete subset of the table records. The query facility compares metadata for different partitions to determine whether sufficiently large differences exist among the partitions, and in appropriate cases selects one or more partitions for separate execution strategies. Preferably, partitions are ranked for separate evaluation using a weighting formula which takes into account: (a) the number of indexes for the partition, (b) recency of change activity, and (c) the size of the partition.
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