32 research outputs found
Recurrence with affine level mappings is P-time decidable for CLP(R)
In this paper we introduce a class of constraint logic programs such that
their termination can be proved by using affine level mappings. We show that
membership to this class is decidable in polynomial time.Comment: To appear in Theory and Practice of Logic Programming (TPLP
NearPM: A Near-Data Processing System for Storage-Class Applications
Persistent Memory (PM) technologies enable program recovery to a consistent
state in a case of failure. To ensure this crash-consistent behavior, programs
need to enforce persist ordering by employing mechanisms, such as logging and
checkpointing, which introduce additional data movement. The emerging near-data
processing (NDP) architec-tures can effectively reduce this data movement
overhead. In this work we propose NearPM, a near data processor that supports
accelerable primitives in crash consistent programs. Using these primitives
NearPM accelerate commonly used crash consistency mechanisms logging,
checkpointing, and shadow-paging. NearPM further reduces the synchronization
overheads between the NDP and the CPU to guarantee persistent ordering by
moving ordering handling near memory. We ensures a correct persist ordering
between CPU and NDP devices, as well as among multiple NDP devices with
Partitioned Persist Ordering (PPO). We prototype NearPM on an FPGA platform.1
NearPM executes data-intensive operations in crash consistency mechanisms with
correct ordering guarantees while the rest of the program runs on the CPU. We
evaluate nine PM workloads, where each work load supports three crash
consistency mechanisms -logging, checkpointing, and shadow paging. Overall,
NearPM achieves 4.3-9.8X speedup in the NDP-offloaded operations and 1.22-1.35X
speedup in end-to-end execution
Tabling with Support for Relational Features in a Deductive Database
Tabling has been acknowledged as a useful technique in the logic programming arena for enhancing both performance and declarative properties of programs. As well, deductive database implementations benefit from this technique for implementing query solving engines. In this paper, we show how unusual operations in deductive systems can be integrated with tabling.Such operations come from relational database systems in the form of null-related (outer) joins, duplicate support and duplicate elimination. The proposal has been implemented as a proof of concept rather than an efficient system in the Datalog Educational System (DES) using Prolog as a development language and its dynamic database
Inherent Complexity of Recursive Queries
AbstractWe give lower bounds on the complexity of certain Datalog queries. Our notion of complexity applies to compile-time optimization techniques for Datalog; thus, our results indicate limitations of these techniques. The main new tool is linear first-order formulas, whose depth (respectively, number of variables) matches the sequential (respectively, parallel) complexity of Datalog programs. We define a combinatorial game (a variant of Ehrenfeucht–Fraı̈ssé games) that can be used to prove nonexpressibility by linear formulas. We thus obtain lower bounds for the sequential and parallel complexity of Datalog queries. We prove syntactically tight versions of our results, by exploiting uniformity and invariance properties of Datalog queries
Workshop on Database Programming Languages
These are the revised proceedings of the Workshop on Database Programming Languages held at Roscoff, Finistère, France in September of 1987. The last few years have seen an enormous activity in the development of new programming languages and new programming environments for databases. The purpose of the workshop was to bring together researchers from both databases and programming languages to discuss recent developments in the two areas in the hope of overcoming some of the obstacles that appear to prevent the construction of a uniform database programming environment. The workshop, which follows a previous workshop held in Appin, Scotland in 1985, was extremely successful. The organizers were delighted with both the quality and volume of the submissions for this meeting, and it was regrettable that more papers could not be accepted. Both the stimulating discussions and the excellent food and scenery of the Brittany coast made the meeting thoroughly enjoyable.
There were three main foci for this workshop: the type systems suitable for databases (especially object-oriented and complex-object databases,) the representation and manipulation of persistent structures, and extensions to deductive databases that allow for more general and flexible programming. Many of the papers describe recent results, or work in progress, and are indicative of the latest research trends in database programming languages.
The organizers are extremely grateful for the financial support given by CRAI (Italy), Altaïr (France) and AT&T (USA). We would also like to acknowledge the organizational help provided by Florence Deshors, Hélène Gans and Pauline Turcaud of Altaïr, and by Karen Carter of the University of Pennsylvania