Topic
Superkey
About: Superkey is a research topic. Over the lifetime, 254 publications have been published within this topic receiving 13496 citations.
Papers published on a yearly basis
Papers
IBM1
TL;DR: In this article, a model based on n-ary relations, a normal form for data base relations, and the concept of a universal data sublanguage are introduced, and certain operations on relations are discussed and applied to the problems of redundancy and consistency in the user's model.
Abstract: Future users of large data banks must be protected from having to know how the data is organized in the machine (the internal representation). A prompting service which supplies such information is not a satisfactory solution. Activities of users at terminals and most application programs should remain unaffected when the internal representation of data is changed and even when some aspects of the external representation are changed. Changes in data representation will often be needed as a result of changes in query, update, and report traffic and natural growth in the types of stored information.Existing noninferential, formatted data systems provide users with tree-structured files or slightly more general network models of the data. In Section 1, inadequacies of these models are discussed. A model based on n-ary relations, a normal form for data base relations, and the concept of a universal data sublanguage are introduced. In Section 2, certain operations on relations (other than logical inference) are discussed and applied to the problems of redundancy and consistency in the user's model.
5,496 citations
TL;DR: The implications of this process when some of the attributes of a string are “synthesized”, i.e., defined solely in terms of attributes of thedescendants of the corresponding nonterminal symbol, while other attributes are ‘inherited’, are examined.
Abstract: “Meaning” may be assigned to a string in a context-free language by defining “attributes” of the symbols in a derivation tree for that string. The attributes can be defined by functions associated with each production in the grammar. This paper examines the implications of this process when some of the attributes are “synthesized”, i.e., defined solely in terms of attributes of thedescendants of the corresponding nonterminal symbol, while other attributes are “inherited”, i.e., defined in terms of attributes of theancestors of the nonterminal symbol. An algorithm is given which detects when such semantic rules could possibly lead to circular definition of some attributes. An example is given of a simple programming language defined with both inherited and synthesized attributes, and the method of definition is compared to other techniques for formal specification of semantics which have appeared in the literature.
2,071 citations
TL;DR: This paper allows the application of the basic relational operators to any relation-valued attribute within a relation, which leads to a (hierarchically) nested relational algebra.
541 citations
TL;DR: The different kinds of joins and the various implementation techniques are surveyed and they are classified based on how they partition tuples from different relations.
Abstract: The join operation is one of the fundamental relational database query operations. It facilitates the retrieval of information from two different relations based on a Cartesian product of the two relations. The join is one of the most diffidult operations to implement efficiently, as no predefined links between relations are required to exist (as they are with network and hierarchical systems). The join is the only relational algebra operation that allows the combining of related tuples from relations on different attribute schemes. Since it is executed frequently and is expensive, much research effort has been applied to the optimization of join processing. In this paper, the different kinds of joins and the various implementation techniques are surveyed. These different methods are classified based on how they partition tuples from different relations. Some require that all tuples from one be compared to all tuples from another; other algorithms only compare some tuples from each. In addition, some techniques perform an explicit partitioning, whereas others are implicit.
522 citations
Patent•
14 Dec 1990
TL;DR: A translator for translating objects defined in Abstract Syntax Notation (ASN) such as ASN.1 to a relational database schema as mentioned in this paper allows persistent storage of object instances as records in relational database.
Abstract: A translator for translating objects defined in Abstract Syntax Notation such as ASN.1 to a relational database schema permits persistent storage of object instances as records in a relational database. Object classes are mapped to entity tables with object instances represented by entity records. Simple attributes are mapped to primitive typed attribute columns and package or group attributes are mapped to separate dependent entity tables. Derived attributes are represented by joins of the parent and child entity records.
514 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2017 | 2 |
| 2016 | 7 |
| 2015 | 6 |
| 2014 | 13 |
| 2013 | 10 |
| 2012 | 7 |