可能性
发表于 2025-3-26 22:38:01
Lydia Ebersbach,Oliver Gassmann,Sven Reineckeuery containment both in the absence and presence of constraints. Containment without constraints for CRPQs is EXPSPACE-complete, as opposed to only NP-complete for relational conjunctive queries. Our past experience with implementing similar algorithms suggests that staying in PSPACE might still be
无目标
发表于 2025-3-27 03:26:44
Andreas Brandenberg,Andreas Herrmann,Georges T. Roos,Jürgen Rösgerons, such as text databases and genome databases, the storage and manipulation of long character sequences is a crucial feature. The issues involved in managing this kind of data are not addressed by traditional database systems, either in theory or in practice. To address these issues, in recent wo
Enliven
发表于 2025-3-27 08:20:32
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机密
发表于 2025-3-27 09:55:53
Hermann Diller,Klaus Backhaus,Matthias Weddelingr seminal paper of 1990. In this area, databases and query languages are defined using read polynomial constraints. As a consequence of a classical result by Tarski, first-order queries in the constraint database model are effectively computable, and their result is within the constraint model..In p
外表读作
发表于 2025-3-27 17:29:29
Miriam Meckel,Philipp Osl,Hubert Österle queries such as transitive closure, and “alternating paths” can be incrementally maintained in a nested relational language, when some auxiliary relations are allowed. In the presence of aggregate functions, even more queries can be maintained, for example, the “same generation” query. In contrast,
洁净
发表于 2025-3-27 21:01:40
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婚姻生活
发表于 2025-3-28 00:12:42
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Prognosis
发表于 2025-3-28 02:29:09
Christian Belz constraints should be preserved. However, this is not always achievable: while BCNF eliminates all redundancies, it may not preserve constraints, and 3NF, which achieves dependency preservation, may not always eliminate all redundancies..Our first goal is to investigate how much redundancy 3NF tole
Grating
发表于 2025-3-28 10:08:45
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不真
发表于 2025-3-28 12:15:36
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