Joined normal form

Abstract

A new on-line query language and storage structure for a database machine is presented. By including a mathematical model in the interpreter the query language has been substantially simplified so that no reference to relation names is necessary. By storing the model as a single joined normal form (JNF) file, it has been possible to exploit the powerful search capability of the Content Addressable File Store (CAFS®; CAFS is a registered trademark of International Computers Limited) database machine.

Database states and their tableaux

“…Our notion of equivalence makes abstraction of which relations are actually stored, and we assume this information is not visible to the user. The user interface is instead a universal relation scheme (as in [2,13,19,21]), and QR is interpreted as the projection of this scheme on R. If we were willing to accept the pure universal relation assumption, then Qs could be obtained by simply projecting the appropriate universal relation on R. Instead, under the weak instance model, we are representing a set of possible universal relations rather than a single one. Conceptually, a correct answer to QR is then the result of projecting on R each one of the infinitely many weak instances for the state and then intersecting all such projections.…”

A relation-based language interpreter for a content addressable file store

“…This process, called Joined Normal Form [7], is to create a relation by joining all the relations through common attributes along the implication arcs. The n-tuples that are lost owing to the absence of common values in shared attributes can be restored by joining them to dummy n-tuples with undefined values in the nonspecified attributes.…”

“…Implication network of P, S, and PS. AP ps\s of each record is a bit vector storing the tags mentioned in [7]. This vector indicates the relations combined within the records as projections.…”

“…Those records that have only some of the attributes and represent information that would have been lost if only the full join had been stored can now be selected from their appropriate relations. To summarize the construction of JNF detailed in [7], consider, for example, the three relations Part, Supplier, and PS (see Figure 6). These would be stored as the relation R, which is the join of all the relations P * S * PS plus the relations Q and T (NB: n means "intersection" and 1 means "complement"), where Q=PnlQ,, which are the parts not linked to suppliers.…”

“…Only the attribute names need be known by the user. More specifically the user cites domain variables such as PART NUMBER not tied to any particular relation [7]. Throughout the paper domain variables will be more briefly referred to as attributes.…”