| 摘要 |
PURPOSE: To easily retrieve a record from a table. CONSTITUTION: A first index is scanned for index entries which satisfy a first state of a query. Thereafter, record addresses (namely, keys) are retrieved for these entries. A future course is determined during or after scanning of the first index. It is determined based on the actual number of retrieved keys or the actual frequency of fetches required for retrieval of these keys. Thus, data records are easily retrieved from the table where one or more indexes exist.
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