Incremental elasticity for array databases

Relational databases benefit significantly from elasticity, whereby they execute on a set of changing hardware resources provisioned to match their storage and processing requirements. Such flexibility is especially attractive for scientific databases because their users often have a no-overwrite storage model, in which they delete data only when their available space is exhausted. This results in a database that is regularly growing and expanding its hardware proportionally. Also, scientific databases frequently store their data as multidimensional arrays optimized for spatial querying. This brings about several novel challenges in clustered, skew-aware data placement on an elastic shared-nothing database. In this work, we design and implement elasticity for an array database. We address this challenge on two fronts: determining when to expand a database cluster and how to partition the data within it. In both steps we propose incremental approaches, affecting a minimum set of data and nodes, while maintaining high performance. We introduce an algorithm for gradually augmenting an array database's hardware using a closed-loop control system. After the cluster adds nodes, we optimize data placement for n-dimensional arrays. Many of our elastic partitioners incrementally reorganize an array, redistributing data only to new nodes. By combining these two tools, the scientific database efficiently and seamlessly manages its monotonically increasing hardware resources.Intel Corporation (Science and Technology Center for Big Data

On indexing highly dynamic multidimensional datasets for interactive analytics

Orientador : Prof. Dr. Luis Carlos Erpen de BonaTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa: Curitiba, 15/04/2016Inclui referências : f. 77-91Área de concentração : Ciência da computaçãoResumo: Indexação de dados multidimensionais tem sido extensivamente pesquisada nas últimas décadas. Neste trabalho, um novo workload OLAP identificado no Facebook é apresentado, caracterizado por (a) alta dinamicidade e dimensionalidade, (b) escala e (c) interatividade e simplicidade de consultas, inadequado para os SGBDs OLAP e técnicas de indexação de dados multidimensionais atuais. Baseado nesse caso de uso, uma nova estratégia de indexação e organização de dados multidimensionais para SGBDs em memória chamada Granular Partitioning é proposta. Essa técnica extende a visão tradicional de partitionamento em banco de dados, particionando por intervalo todas as dimensões do conjunto de dados e formando pequenos blocos que armazenam dados de forma não coordenada e esparsa. Desta forma, é possível atingir altas taxas de ingestão de dados sem manter estrutura auxiliar alguma de indexação. Este trabalho também descreve como um SGBD OLAP capaz de suportar um modelo de dados composto por cubos, dimensões e métricas, além de operações como roll-ups, drill-downs e slice and dice (filtros) eficientes pode ser construído com base nessa nova técnica de organização de dados. Com objetivo de validar experimentalmente a técnica apresentada, este trabalho apresenta o Cubrick, um novo SGBD OLAP em memória distribuída e otimizada para a execução de consultas analíticas baseado em Granular Partitioning, escritas desde a primeira linha de código para este trabalho. Finalmente, os resultados de uma avaliação experimental extensiva contendo conjuntos de dados e consultas coletadas de projetos pilotos que utilizam Cubrick é apresentada; em seguida, é mostrado que a escala desejada pode ser alcançada caso os dados sejam organizados de acordo com o Granular Partitioning e o projeto seja focado em simplicidade, ingerindo milhões de registros por segundo continuamente de uxos de dados em tempo real, e concorrentemente executando consultas com latência inferior a 1 segundo.Abstrct: Indexing multidimensional data has been an active focus of research in the last few decades. In this work, we present a new type of OLAP workload found at Facebook and characterized by (a) high dynamicity and dimensionality, (b) scale and (c) interactivity and simplicity of queries, that is unsuited for most current OLAP DBMSs and multidimensional indexing techniques. To address this use case, we propose a novel multidimensional data organization and indexing strategy for in-memory DBMSs called Granular Partitioning. This technique extends the traditional view of database partitioning by range partitioning every dimension of the dataset and organizing the data within small containers in an unordered and sparse fashion, in such a way to provide high ingestion rates and indexed access through every dimension without maintaining any auxiliary data structures. We also describe how an OLAP DBMS able to support a multidimensional data model composed of cubes, dimensions and metrics and operations such as roll-up, drill-down as well as efficient slice and dice filtering) can be built on top of this new data organization technique. In order to experimentally validate the described technique we present Cubrick, a new in-memory distributed OLAP DBMS for interactive analytics based on Granular Partitioning we have written from the ground up at Facebook. Finally, we present results from a thorough experimental evaluation that leveraged datasets and queries collected from a few pilot Cubrick deployments. We show that by properly organizing the dataset according to Granular Partitioning and focusing the design on simplicity, we are able to achieve the target scale and store tens of terabytes of in-memory data, continuously ingest millions of records per second from realtime data streams and still execute sub-second queries

A Modular Parallel Pipeline Architecture for GWAS Applications in a Cluster Environment

A Genome Wide Association Study (GWAS) is an important bioinformatics method to associate variants with traits, identify causes of diseases and increase plant and crop production. There are several optimizations for improving GWAS performance, including running applications in parallel. However, it can be difficult for researchers to utilize different data types and workflows using existing approaches. A potential solution for this problem is to model GWAS algorithms as a set of modular tasks. In this thesis, a modular pipeline architecture for GWAS applications is proposed that can leverage a parallel computing environment as well as store and retrieve data using a shared data cache. To show that the proposed architecture increases performance of GWAS applications, two case studies are conducted in which the proposed architecture is implemented on a bioinformatics pipeline package called TASSEL and a GWAS application called FaST-LMM using both Apache Spark and Dask as the parallel processing framework and Redis as the shared data cache. The case studies implement parallel processing modules and shared data cache modules according to the specifications of the proposed architecture. Based on the case studies, a number of experiments are conducted that compare the performance of the implemented architecture on a cluster environment with the original programs. The experiments reveal that the modified applications indeed perform faster than the original sequential programs. However, the modified applications do not scale with cluster resources, as the sequential part of the operations prevent the parallelization from having linear scalability. Finally, an evaluation of the architecture was conducted based on feedback from software developers and bioinformaticians. The evaluation reveals that the domain experts find the architecture useful; the implementations have sufficient performance improvement and they are also easy to use, although a GUI based implementation would be preferable

The 1995 Science Information Management and Data Compression Workshop

This document is the proceedings from the 'Science Information Management and Data Compression Workshop,' which was held on October 26-27, 1995, at the NASA Goddard Space Flight Center, Greenbelt, Maryland. The Workshop explored promising computational approaches for handling the collection, ingestion, archival, and retrieval of large quantities of data in future Earth and space science missions. It consisted of fourteen presentations covering a range of information management and data compression approaches that are being or have been integrated into actual or prototypical Earth or space science data information systems, or that hold promise for such an application. The Workshop was organized by James C. Tilton and Robert F. Cromp of the NASA Goddard Space Flight Center

Proceedings of the 1993 Conference on Intelligent Computer-Aided Training and Virtual Environment Technology

The volume 2 proceedings from the 1993 Conference on Intelligent Computer-Aided Training and Virtual Environment Technology are presented. Topics discussed include intelligent computer assisted training (ICAT) systems architectures, ICAT educational and medical applications, virtual environment (VE) training and assessment, human factors engineering and VE, ICAT theory and natural language processing, ICAT military applications, VE engineering applications, ICAT knowledge acquisition processes and applications, and ICAT aerospace applications

Recycling texts: human evaluation of example-based machine translation subtitles for DVD

This project focuses on translation reusability in audiovisual contexts. Specifically, the project seeks to establish (1) whether target language subtitles produced by an EBMT system are considered intelligible and acceptable by viewers of movies on DVD, and (2)whether a relationship exists between the ‘profiles’ of corpora used to train an EBMT system, on the one hand, and viewers’ judgements of the intelligibility and acceptability of the subtitles produced by the system, on the other. The impact of other factors, namely: whether movie-viewing subjects have knowledge of the soundtrack language; subjects’ linguistic background; and subjects’ prior knowledge of the (Harry Potter) movie clips viewed; is also investigated. Corpus profiling is based on measurements (partly using corpus-analysis tools) of three characteristics of the corpora used to train the EBMT system: the number of source language repetitions they contain; the size of the corpus; and the homogeneity of the corpus (independent variables). As a quality control measure in this prospective profiling phase, we also elicit human judgements (through a combined questionnaire and interview) on the quality of the corpus data and on the reusability in new contexts of the TL subtitles. The intelligibility and acceptability of EBMT-produced subtitles (dependent variables) are, in turn, established through end-user evaluation sessions. In these sessions 44 native German-speaking subjects view short movie clips containing EBMT-generated German subtitles, and following each clip answer questions (again, through a combined questionnaire and interview) relating to the quality characteristics mentioned above. The findings of the study suggest that an increase in corpus size along with a concomitant increase in the number of source language repetitions and a decrease in corpus homogeneity, improves the readability of the EBMT-generated subtitles. It does not, however, have a significant effect on the comprehensibility, style or wellformedness of the EBMT-generated subtitles. Increasing corpus size and SL repetitions also results in a higher number of alternative TL translations in the corpus that are deemed acceptable by evaluators in the corpus profiling phase. The research also finds that subjects are more critical of subtitles when they do not understand the soundtrack language, while subjects’ linguistic background does not have a significant effect on their judgements of the quality of EBMT-generated subtitles. Prior knowledge of the Harry Potter genre, on the other hand, appears to have an effect on how viewing subjects rate the severity of observed errors in the subtitles, and on how they rate the style of subtitles, although this effect is training corpus-dependent. The introduction of repeated subtitles did not reduce the intelligibility or acceptability of the subtitles. Overall, the findings indicate that the subtitles deemed the most acceptable when evaluated in a non-AVT environment (albeit one in which rich contextual information was available) were the same as the subtitles deemed the most acceptable in an AVT environment, although richer data were gathered from the AVT environment