| 摘要 |
An approximate querying method comprising grouping tuples within a database according to grouping attributes, determining how many tuples are needed to represent each group, selecting the tuples from a corresponding group to create a database sample, and querying the database sample. The database sample yields statistically unbiased answers when queried. The sample may be created and maintained without a priori knowledge of the data distribution within the database or the queries to be performed.
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