Data Expiration and Aggregate Queries
نویسنده
چکیده
We investigate the space requirements for summaries needed for maintaining exact answers to aggregate queries over histories of relational databases. We show that, in general, a super-logarithmic lower bound (in the length of the history) on space needed to maintain a summary of the history in order to be able to maintain answers to counting queries. We also develop a natural restriction on the use of aggregation that allows for a logarithmic upper bound and in turn maintaining the summary of the history using counters.
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تاریخ انتشار 2009