PODS

We propose compilation methods for supporting set terms in Horn clause programs, without using general-purpose set matching algorithms, which tend to run in times exponential in the size of the participating sets Instead, we take the approach of ...

The set-height of a complex object type is defined to be its level of nesting of the set construct. In a query of the complex object calculus which maps a database D to an output type T, an intermediate type is a type which is used by some variable of ...

A database query is safe if its result consists of a finite set of tuples. If a query is expressed using a set of pure Horn Clauses, the problem of determining query safety is, in general, undecidable. In this paper we consider a slightly stronger ...

We discuss deductive databases with one fixed occurrence of a monadic function symbol(successor) per predicate Databases of this kind can be used in a natural way to model simple patterns of events repeated in time, and this is why we term them temporal...

Selection of an appropriate order for the evaluation of subgoals in a logical rule frequently is essential for efficiency. We formulate the problem as one of feasible subgoal orders and show that the question is inherently exponential in time. The proof ...

Rule-goal graphs are the central data structures used in the NAIL′ system, a knowledge-base system being developed at Stanford University They are constructed while testing the applicability of capture rules, and traversed while generating ICODE to ...

The problem of pushing projections in recursive rules has received little attention. The objective of this paper is to motivate this problem and present some (partial) solutions. We consider programs with function-free rules, also known as Datalog ...

In this paper we argue with a basic premise in logic programming research that the meaning of a program can be inferred from its syntax alone. We show that users may have a variety of intended models for programs and that a single program may give ...

Recently Litwin and Lomet proposed the Bounded Disorder (BD) file organization which uses a combination of hashing and tree indexing Lomet provided an approximate analysis with a mention of the difficulty involved in exact modeling and analysis. The ...

We propose a new algorithmic framework for database concurrency control using multiple versions of data items and a serialization graph of the transactions as a synchronization technique, which generalizes all concurrency control methods known so far. ...

The M-pitfall protocol (MPP) is the most general homogeneous non-two-phase locking protocol which supports shared and exclusive locks. It has two major disadvantages: it is not deadlock-free and it has the paradoxical property that concurrency is often ...

This paper describes my vision of the current state of object-oriented database research. I first briefly define this field by its objectives, and relate it to other database subfields. I describe what I consider to be the main characteristics of an ...

A class of cover embedding database schemes, called independence-reducible, is proposed and is proven to be bounded and algebraic-maintainable, and therefore is highly desirable with respect to query answering and constraint enforcement. This class of ...

A generalized approach to the decomposition of relational schemata is developed in which the component views may be defined using both restriction and projection operators, thus admitting both horizontal and vertical decompositions. The realization of ...

We propose a very simple formalism based on parameterized types and a rule-based algebra to explain the storage structures and algorithms of database management systems. Implementations of DBMSs are expressed as equations If all functions referenced in ...

In this paper we investigate the problem of synchronising transactions in an object base. An object base is a collection of objects, much the way a database is a collection of data. An object, for our purposes, consists of a collection of variables (...

We define a new locking protocol that permits more concurrency than existing commutativity-based protocols. The protocol uses timestamps generated when transactions commit to provide more information about the serialization order of transactions, and ...

Set manipulation consists of the actions insert, delete, and member on keys. We propose a concurrent set manipulation algorithm that uses no locking at all and requires no aborts, relying instead on atomic read-modify-write operations on single (data) ...

A general logic program (abbreviated to “program” hereafter) is a set of rules that have both positive and negative subgoals. It is common to view a deductive database as a general logic program consisting of rules (IDB) sitting above elementary ...

There is a fixpoint semantics for DATALOG programs with negation that is a natural generalization of the standard semantics for DATALOG programs without negation. We show that, unfortunately, several compelling complexity-theoretic obstacles rule out ...

The need for control in logic programs is now being recognized. This is particularly evident when one focuses on allowing updates in logic programs. In this paper we propose a language DatalogA which is an extension of Datalog with updates to base ...

In this paper we discuss the optimization of multiple-relation multiple-disjunct queries in a relational database system. Since optimization techniques for conjunctive (single disjunct) queries in relational databases are well known [Smith75, Wong76, ...

Present database systems process all the data related to a query before giving out responses. As a result, the size of the data to be processed becomes excessive for real-time/time-constrained environments. A new methodology is needed to cut down ...

The focus of this paper is on demonstrating the existence of methods for stably performing set and multiset operations on sorted files of data in both optimal time and optimal extra space. It is already known that stable merging and stable duplicate-key ...

We introduce the concept of a version graph to model the problem of minimising the space and version regeneration cost for database version control. We show that, in general, this problem and several of its variations are NP-complete. Motivated by the ...