A CORE PROTOTYPE IMPLEMENTATION OF AN EXTENDED RELATIONAL DATABASE LANGUAGE FOR EFFICIENT MANIPULATION OF CONTAINMENT AND COMPOSITE STRUCTURES
Date
1996-12-01
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Abstract
The core prototype implementation of an extended relational data base
system is described. The full data model allows for restricted unnormalized
relations. Essentially attributes that are sets or lists of atomic attributes
are allowed but not attributes that are relations. There is support for both
inheritance and composite entities. Manipulation languages are SQL and a
separate new SQL language subset for efficient manipulation of
containment structures.
The language subset has a predicate calculus expression structure, but
allows the use of genitive relations to model containment relationships and
facilitate application of natural quantifiers to containment sets. A
genitive relation is a relation that is the equivalent to the genitive
case grammatical construct in natural language.
In the query processor a query decomposition technique was employed.
Declarative language expressions involving naturally quantified genitive
relation clauses for one-to-many relationships, both composite and
non composite, both recursive and nonrecursive, and for subset genitive
relations, can be reduced. The natural quantifiers are the
quantifiers of natural language and the prototype implements 14 basic
types including universal and existential quantifiers. The query processor
translates declarative language expressions to Extended Relational
Algebra (ERA) routines. ERA differs from conventional relational algebra
in that it has a possibility join operation, as well as two operations
involving quantifiers, namely group select and subgroup select operations.
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Computer Science