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Summary form only given. Consider a universe of items, each of which is associated with a weight, and a database consisting of subsets of these items. Given a query set, a weighted set similarity query identifies either (i) all sets in the database whose normalized similarity to the query set is above a pre-specified threshold, or (ii) the sets in the database with the k highest similarity values...
A self-healing system is a grand-challenge vision where the system will detect, diagnose, and repair performance problems and hardware/software faults automatically. These systems take humans out of the failure-recovery loop, enabling recovery to happen at fast machine timescales rather than slower human timescales. Are self-healing database systems Utopia or just a hard puzzle to solve? We argue...
In database systems that support fine-grained access controls, each user has access rights that determine which tuples are accessible and which are inaccessible. Queries are answered as if the inaccessible tuples are not present in the database. Thus, users with different access rights may get different answers to a given query. To process queries efficiently in the presence of fine-grained access...
We introduce a framework for reordering join pipelines at runtime in a database system. This framework incorporates novel techniques for simulating the execution of a join pipeline using random samples and statistical summaries. Our simulation techniques provide accurate runtime cardinality estimates along all alternative execution paths of a join pipeline. These estimates are then utilized to compare...
Auditing the changes to a database is critical for identifying malicious behavior, maintaining data quality, and improving system performance. But an accurate audit log is a historical record of the past that can also pose a serious threat to privacy. Policies which limit data retention conflict with the goal of accurate auditing, and data owners have to carefully balance the need for policy compliance...
Online approaches to physical design tuning have received considerable attention in the recent literature, with a focus on the problem of online index selection. However, it is difficult to draw conclusions on the relative merits of the proposed techniques, as they have been evaluated in isolation using different methodologies. In this paper, we make two concrete contributions to address this issue...
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