Naslov
Semantically Unconnected Relational Schemes

Autori
Mateljan, Vladimir ; Tkalac, Slavk ; Čubrilo, Mirko

Vrsta, podvrsta i kategorija rada
Poglavlja u knjigama, znanstveni

Knjiga
Zbornik radova "Težakovi dani"

Urednik/ci
Tkalac, Slavko ; Lasić-Lazić, Jadranka

Izdavač
Zavod za informacijske studije Odsjeka za informacijske i komunikacijske znanosti Filozofskog fakulteta Sveučilišta u Zagrebu

Grad
Zagreb

Godina
2002

Raspon stranica
21-28

ISBN
953-175-182-X

Ključne riječi
functional dependences, relational scheme, losless join
(funkcijska zavisnost, relacijska shema, gubitak zavisnosti)

Sažetak
By means of normalizing data the relational scheme is decomposed into several smaller and more regular sub-schemes. During the decomposition there should be no loss of information. Using the Aho, Beri and Ullman algorithm it is possible to prove that the initial set of information has been kept. Using Rissanen criterion of component independence, it is possible to prove the same thing in a far simpler and faster way. Therefore, Rissanen test is of extreme importance in the process of designing a database. We will show in the work that Rissanen test is sufficient but not a necessary condition in proving the reversibility of the decomposition of the relational scheme, i.e. we will show that the decomposition of the relational scheme can be reversible even if the Rissanen test is not met.

Izvorni jezik
Engleski

Znanstvena područja
Informacijske i komunikacijske znanosti

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