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Update semantics of relational views (1981)
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| Venue: | ACM Transactions on Database Systems |
| Citations: | 247 - 4 self |
BibTeX
@ARTICLE{Bancilhon81updatesemantics,
author = {F. Bancilhon and N. Spyratos},
title = {Update semantics of relational views},
journal = {ACM Transactions on Database Systems},
year = {1981},
volume = {6},
pages = {557--575}
}
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Abstract
A database view is a portion of the data structured in a way suitable to a specific application. Updates on views must be translated into updates on the underlying database. This paper studies the translation process in the relational model. The procedure is as follows: first, a “complete ” set of updates is defined such that (i) together with every update the set contains a “return ” update, that is, one that brings the view back to the original state; (ii) given two updates in the set, their composition is also in the set. To translate a complete set, we define a mapping called a “translator, ” that associates with each view update a unique database update called a “translation. ” The constraint on a translation is to take the database to a state mapping onto the updated view. The constraint on the translator is to be a morphism. We propose a method for defining translators. Together with the user-defined view, we define a “complementary ” view such that the database could be computed from the view and its complement. We show that a view can have many different complements and that the choice of a complement determines an update policy. Thus, we fix a view complement and we define the translation of a given view update in such a way that the complement remains invariant (“translation under constant complemen$‘). The main result of the paper states that, given a complete set U of view updates, U has a translator if and only if U is translatable under constant complement.
Keyphrases
relational view update semantics complete set view update underlying database update policy user-defined view main result view complement constant complement complementary view many different complement relational model return update unique database update specific application paper study updated view constant complemen database view original state translation process state mapping
