Showing papers on "Tuple published in 1977"

Domain-oriented relational languages

Abstract: A view of the semantics of a relational data base consists in considering that the data base domains represent the sets of objects of the subject matter and that the relations represent various kinds of associations among these objects. This view is supported by query languages where each variable ranges on a domain of the relational data base and predicates correspond to the associations modeled by relations. This paper defines two domain-oriented relational languages. DRC is a many-sorted calculus, where the structural role of domains is emphasized by defining types for variables and type-checking rules. ILL is an English-like language, which is wholly built upon a structure of expressions nested inside other expressions. "Domain-languages" are contrasted with "tuple languages", which manipulate as basic objects the relation n-tuples. Directly manipulating domains and domain values interacts more directly with the semantics expressed by the relations and produces simpler and more English-like languages.

A scan-driven sort facility for a relational database system

Abstract: In this paper the design and implementation aspects of an integrated sort package are described which was implemented by the author as a part of an experimental relational database system called System R. The sort facility developed for variable length sort keys and tuples is discussed with regard to its anticipated use in relational database systems. It is considered to be a powerful tool to implement complex relational operations like join and projection and to support the dynamic creation of access paths and the loading and reorganizing of data clustered by field values. The input loop of the sort can be driven by various scans which allow the filtering of qualified tuples according to disjunctive normal forms of simple search arguments. Various aspects of the integration with storage and transaction management, locking and logging components are described. A number of design decisions for the sort facility concerning sorting, peerage, and merging techniques are discussed. Finally, some implementation aspects for sorting variable length keys consisting of a number of distributed fields are pointed out.

DBC Software Requirement for Supporting Relational Databases.

Abstract: : This is the final report of a series of work aimed at demonstrating the capabilities of a back-end database computer (DBC) in supporting known data models and systems. In the previous two reports, it was shown that existing hierarchical and network database management systems, in particular, the Information Management System (IMS) of IBM and DMS1100 of UNIVAC, can be supported on the DBC with a vastly improved performance. In this final report, we study a relational database management system, namely System R, with a view to supporting such a system on the DBC. The early sections of this report are introductory in nature. The representation of relational tuples in the DBC is quite straightforward. The data items of every tuple are converted to attribute-value pairs to form a single DBC record. Two special attribute-value pairs are also included in each DBC record in order to indicate the relation to which the corresponding tuple belongs, and to provide certain clustering information. User transactions in the data sublanguage, called SEQUEL, are converted to a series of DBC commands. The commands are so structured that the DBC can simultaneously access a number of records, the contents of which satisfy the predicates in a SEQUEL query. Given a particular command, the DBC uses its directory to determine the portions of its secondary storage that need to be content-searched.