Titlebook: Constraint Databases; Gabriel Kuper,Leonid Libkin,Jan Paredaens Book 2000 Springer-Verlag Berlin Heidelberg 2000 Datalog.GIS.Logik.SQL.alg

IOTA

绿州

textile

治愈

Genetic Aspects of Uncommon Diseasestime can easily be introduced as additional attributes in the relational model. Of course, specific operations need to be performed with temporal attributes, such as dealing with date formats, but such operations are not really problematic, and have long been available in commercial systems. Neverth

蔓藤图饰

Diagnostic of Urogenital Tuberculosis,, which is then optimized and evaluated. As we have seen in Section 2.4.4, if we consider unrestricted databases, the classical equivalence between the algebra and the calculus carries over easily. Furthermore, all the algebraic operations described in in Section 2.4.4 can be effectively evaluated o

AV-node

围巾

Aggregate Languages for Constraint Databasesry languages give a natural analog of relational calculus in the geometric context, a crucial question concerns how to extend standard aggregation constructs from the relational model to the geometric setting. This question has two components.

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and Constraintsn for “.base . programs.” In Section 2.8 we gave the basic definitions for ., and we also saw that the language is not closed for important constraint classes such as linear equalities. We have also seen some results on restricting the language, and the resulting expressive power, in Section 4.4.1.

破译

compel

I/O-Efficient Algorithms for CDBstabases, it is possible to design theoretically . practically efficient algorithms. In addition, we show that certain problems are . hard with the result that no theoretically efficient algorithms are possible for them. This chapter has three parts: