10381 Summary and Abstracts Collection -- Robust Query Processing

Dagstuhl seminar 10381 on robust query processing (held 19.09.10 - 24.09.10) brought together a diverse set of researchers and practitioners with a broad range of expertise for the purpose of fostering discussion and collaboration regarding causes, opportunities, and solutions for achieving robust query processing. The seminar strove to build a unified view across the loosely-coupled system components responsible for the various stages of database query processing. Participants were chosen for their experience with database query processing and, where possible, their prior work in academic research or in product development towards robustness in database query processing. In order to pave the way to motivate, measure, and protect future advances in robust query processing, seminar 10381 focused on developing tests for measuring the robustness of query processing. In these proceedings, we first review the seminar topics, goals, and results, then present abstracts or notes of some of the seminar break-out sessions. We also include, as an appendix, the robust query processing reading list that was collected and distributed to participants before the seminar began, as well as summaries of a few of those papers that were contributed by some participants

Guidance for the inspection of independent schools, from September 2010

"This guidance sets out the way the inspectorate will inspect independent schools for the six-year inspection cycle from 2010. It relates to the inspection of all independent schools in Wales, including those that provide wholly or mainly for pupils with special educational needs (SEN). It will be reviewed during 2012-2013 in preparation for the second half of the inspection cycle." - introduction

Generating code for holistic query evaluation

Abstract — We present the application of customized code generation to database query evaluation. The idea is to use a collection of highly efficient code templates and dynamically instantiate them to create query- and hardware-specific source code. The source code is compiled and dynamically linked to the database server for processing. Code generation diminishes the bloat of higher-level programming abstractions necessary for implementing generic, interpreted, SQL query engines. At the same time, the generated code is customized for the hardware it will run on. We term this approach holistic query evaluation. We present the design and development of a prototype system called HIQUE, the Holistic Integrated Query Engine, which incorporates our proposals. We undertake a detailed experimental study of the system’s performance. The results show that HIQUE satisfies its design objectives, while its efficiency surpasses that of both wellestablished and currently-emerging query processing techniques. I

Scheduling threads for constructive cache sharing on CMPs

In chip multiprocessors (CMPs), limiting the number of offchip cache misses is crucial for good performance. Many multithreaded programs provide opportunities for constructive cache sharing, in which concurrently scheduled threads share a largely overlapping working set. In this paper, we compare the performance of two state-of-the-art schedulers proposed for fine-grained multithreaded programs: Parallel Depth First (PDF), which is specifically designed for constructive cache sharing, and Work Stealing (WS), which is a more traditional design. Our experimental results indicate that PDF scheduling yields a 1.3 - 1.6X performance improvement relative to WS for several fine- grain parallel benchmarks on projected future CMP configurations; we also report several issues that may limit the advantage of PDF in certain applications. These results also indicate that PDF more effectively utilizes off-chip bandwidth, making it possible to trade-off on-chip cache for a larger number of cores. Moreover, we find that task granularity plays a key role in cache performance. Therefore, we present an automatic approach for selecting effective grain sizes, based on a new working set profiling algorithm that is an order of magnitude faster than previous approaches. This is the first paper demonstrating the effectiveness of PDF on real benchmarks, providing a direct comparison between PDF and WS, revealing the limiting factors for PDF in practice, and presenting an approach for overcoming these factors. Copyright 2007 ACM

An Orchestral Conductor’s Guide to the James/Daehler Edition Of The Hinrichs and Winkler Compilation Score to the 1925 Silent Film \u3ci\u3eThe Phantom of the Opera\u3c/i\u3e

The performance of silent film scores with live screenings of silent films is an artform that is still enjoyed by 21st century audiences. One of the most frequently performed examples of this is The Phantom of the Opera (1925). In addition to being an iconic film in the history of Hollywood cinema, this film possesses a full orchestral score which allows it to have accessibility for mainstream concert-hall performance. Live film music has become increasingly popular in mainstream concert halls, and there is a consistent need for accessible repertoire in this medium. Performing a silent film with live orchestral accompaniment is also an artform that has largely remained unchanged since the 1920s. Silent film scores do not generally possess aids such as click tracks or punch and streamer systems to assist a conductor. As a result of this, modern-day conductors may be unfamiliar with methods needed to synchronize an orchestral score with a silent film on a screen. The purpose of this study is to provide conductors with a guide to one of the earliest known scores to The Phantom of the Opera to help make the score more accessible for mainstream performance. This study provides an overview of the score, a breakdown of the score’s musical and aesthetic traits to allow for optimum synchronization with the film, and a list of errata for ease of performance

Engineering Aggregation Operators for Relational In-Memory Database Systems

In this thesis we study the design and implementation of Aggregation operators in the context of relational in-memory database systems. In particular, we identify and address the following challenges: cache-efficiency, CPU-friendliness, parallelism within and across processors, robust handling of skewed data, adaptive processing, processing with constrained memory, and integration with modern database architectures. Our resulting algorithm outperforms the state-of-the-art by up to 3.7x