| 摘要 |
Techniques described herein adaptively select materialized view fragments for persistent maintenance. During an interval of time, the selected fragments are persistently maintained in the database system, while the other non-selected fragments are not persistently maintained as materialized view fragments. Over time, the composition of the set of selected fragments may change. As queries are executed in the database system over an interval of time, statistics including the frequency of access of each currently selected fragment during that interval are generated. At the start of the next interval of time, based on these statistics, some currently selected fragments may be unselected. Some currently non-selected fragments of one or more candidate materialized views may be selected based on the statistics. For the next interval, the newly unselected fragments cease to be persistently maintained as materialized view fragments, while the newly selected fragments begin to be persistently maintained as materialized view fragments.
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