Query-Time Data Integration

Today, data is collected in ever increasing scale and variety, opening up enormous potential for new insights and data-centric products. However, in many cases the volume and heterogeneity of new data sources precludes up-front integration using traditional ETL processes and data warehouses. In some cases, it is even unclear if and in what context the collected data will be utilized. Therefore, there is a need for agile methods that defer the effort of integration until the usage context is established. This thesis introduces Query-Time Data Integration as an alternative concept to traditional up-front integration. It aims at enabling users to issue ad-hoc queries on their own data as if all potential other data sources were already integrated, without declaring specific sources and mappings to use. Automated data search and integration methods are then coupled directly with query processing on the available data. The ambiguity and uncertainty introduced through fully automated retrieval and mapping methods is compensated by answering those queries with ranked lists of alternative results. Each result is then based on different data sources or query interpretations, allowing users to pick the result most suitable to their information need. To this end, this thesis makes three main contributions. Firstly, we introduce a novel method for Top-k Entity Augmentation, which is able to construct a top-k list of consistent integration results from a large corpus of heterogeneous data sources. It improves on the state-of-the-art by producing a set of individually consistent, but mutually diverse, set of alternative solutions, while minimizing the number of data sources used. Secondly, based on this novel augmentation method, we introduce the DrillBeyond system, which is able to process Open World SQL queries, i.e., queries referencing arbitrary attributes not defined in the queried database. The original database is then augmented at query time with Web data sources providing those attributes. Its hybrid augmentation/relational query processing enables the use of ad-hoc data search and integration in data analysis queries, and improves both performance and quality when compared to using separate systems for the two tasks. Finally, we studied the management of large-scale dataset corpora such as data lakes or Open Data platforms, which are used as data sources for our augmentation methods. We introduce Publish-time Data Integration as a new technique for data curation systems managing such corpora, which aims at improving the individual reusability of datasets without requiring up-front global integration. This is achieved by automatically generating metadata and format recommendations, allowing publishers to enhance their datasets with minimal effort. Collectively, these three contributions are the foundation of a Query-time Data Integration architecture, that enables ad-hoc data search and integration queries over large heterogeneous dataset collections

Providing Insight into the Performance of Distributed Applications Through Low-Level Metrics

The field of high-performance computing (HPC) has always dealt with the bleeding edge of computational hardware and software to achieve the maximum possible performance for a wide variety of workloads. When dealing with brand new technologies, it can be difficult to understand how these technologies work and why they work the way they do. One of the more prevalent approaches to providing insight into modern hardware and software is to provide tools that allow developers to access low-level metrics about their performance. The modern HPC ecosystem supports a wide array of technologies, but in this work, I will be focusing on two particularly influential technologies: The Message Passing Interface (MPI), and Graphical Processing Units (GPUs).For many years, MPI has been the dominant programming paradigm in HPC. Indeed, over 90% of applications that are a part of the U.S. Exascale Computing Project plan to use MPI in some fashion. The MPI Standard provides programmers with a wide variety of methods to communicate between processes, along with several other capabilities. The high-level MPI Profiling Interface has been the primary method for profiling MPI applications since the inception of the MPI Standard, and more recently the low-level MPI Tool Information Interface was introduced.Accelerators like GPUs have been increasingly adopted as the primary computational workhorse for modern supercomputers. GPUs provide more parallelism than traditional CPUs through a hierarchical grid of lightweight processing cores. NVIDIA provides profiling tools for their GPUs that give access to low-level hardware metrics.In this work, I propose research in applying low-level metrics to both the MPI and GPU paradigms in the form of an implementation of low-level metrics for MPI, and a new method for analyzing GPU load imbalance with a synthetic efficiency metric. I introduce Software-based Performance Counters (SPCs) to expose internal metrics of the Open MPI implementation along with a new interface for exposing these counters to users and tool developers. I also analyze a modified load imbalance formula for GPU-based applications that uses low-level hardware metrics provided through nvprof in a hierarchical approach to take the internal load imbalance of the GPU into account

A Domain-Specific Language for Do-It-Yourself Analytical Mashups

The increasing amount and variety of data available in the web leads to new possibilities in end-user focused data analysis. While the classic data base technologies for data integration and analysis (ETL and BI) are too complex for the needs of end users, newer technologies like web mashups are not optimal for data analysis. To make productive use of the data available on the web, end users need easy ways to find, join and visualize it. We propose a domain specific language (DSL) for querying a repository of heterogeneous web data. In contrast to query languages such as SQL, this DSL describes the visualization of the queried data in addition to the selection, filtering and aggregation of the data. The resulting data mashup can be made interactive by leaving parts of the query variable. We also describe an abstraction layer above this DSL that uses a recommendation-driven natural language interface to reduce the difficulty of creating queries in this DSL

Regulierung der Anlageberatung und behavioral finance: Anlegerleitbild: homo oeconomicus vs. Realität

Die Arbeit untersucht die Regulierung der Anlageberatung und stellt dar, warum es dabei trotz bester Absichten des Gesetzgebers bisher nicht gelungen ist, einen Rechtsrahmen zu schaffen, der die Anzahl an enttäuschten und getäuschten Anlegern verringert. Dabei wird auf die Erkenntnisse der immer weiter verbreiteten behavioral finance (Lehre vom Verhalten der Anleger) zurückgegriffen. Die Untersuchung zeigt, wie und warum Wunsch und Wirklichkeit beim Anlegerleitbild des Gesetzgebers und der Regulierung der Anlageberatung auseinandergehen. Um das Verhalten der Akteure vor, während und nach der Anlageberatung steuern zu können, muss man deren Verhaltensweisen verstehen und mit diesem Wissen sowohl die bisher verwendeten Instrumente des Anlegerschutzes (Stichwort: Informationspflichten) anpassen, als auch neue Methoden (z.B. choice architecture) heranziehen. Das Buch wendet sich an den Gesetzgeber und die interessierten Rechtswissenschaftler, daneben aber auch an die mit der Anlageberatung befassten Gerichte und Anwälte und zu guter Letzt auch an Anleger, die etwas über sich lernen wollen

Frontiers in Crowdsourced Data Integration

There is an ever-increasing amount and variety of open web data available that is insufficiently examined or not considered at all in decision making processes. This is because of the lack of end-user friendly tools that help to reuse this public data and to create knowledge out of it. Therefore, we propose a schema-optional data repository that provides the flexibility necessary to store and gradually integrate heterogeneous web data. Based on this repository, we propose a semi-automatic schema enrichment approach that efficiently augments the data in a “pay-as-you-go” fashion. Due to the inherently appearing ambiguities we further propose a crowd-based verification component that is able to resolve such conflicts in a scalable manner.Die stetig wachsende Zahl offen verfügbarer Webdaten findet momentan viel zu wenig oder gar keine Berücksichtigung in Entscheidungsprozessen. Der Grund hierfür ist insbesondere in der mangelnden Unterstützung durch anwenderfreundliche Werkzeuge zu finden, die diese Daten nutzbar machen und Wissen daraus genieren können. Zu diesem Zweck schlagen wir ein schemaoptionales Datenrepositorium vor, welches ermöglicht, heterogene Webdaten zu speichern sowie kontinuierlich zu integrieren und mit Schemainformation anzureichern. Auf Grund der dabei inhärent auftretenden Mehrdeutigkeiten, soll dieser Prozess zusätzlich um eine Crowd-basierende Verifikationskomponente unterstützt werden

Top-k Entity Augmentation using Consistent Set Covering

Entity augmentation is a query type in which, given a set of entities and a large corpus of possible data sources, the values of a missing attribute are to be retrieved. State of the art methods return a single result that, to cover all queried entities, is fused from a potentially large set of data sources. We argue that queries on large corpora of heterogeneous sources using information retrieval and automatic schema matching methods can not easily return a single result that the user can trust, especially if the result is composed from a large number of sources that user has to verify manually. We therefore propose to process these queries in a Top-k fashion, in which the system produces multiple minimal consistent solutions from which the user can choose to resolve the uncertainty of the data sources and methods used. In this paper, we introduce and formalize the problem of consistent, multi-solution set covering, and present algorithms based on a greedy and a genetic optimization approach. We then apply these algorithms to Web table-based entity augmentation. The publication further includes a Web table corpus with 100M tables, and a Web table retrieval and matching system in which these algorithms are implemented. Our experiments show that the consistency and minimality of the augmentation results can be improved using our set covering approach, without loss of precision or coverage and while producing multiple alternative query results

OPEN—Enabling Non-expert Users to Extract, Integrate, and Analyze Open Data

Government initiatives for more transparency and participation have lead to an increasing amount of structured data on the web in recent years. Many of these datasets have great potential. For example, a situational analysis and meaningful visualization of the data can assist in pointing out social or economic issues and raising people’s awareness. Unfortunately, the ad-hoc analysis of this so-called Open Data can prove very complex and time-consuming, partly due to a lack of efficient system support.On the one hand, search functionality is required to identify relevant datasets. Common document retrieval techniques used in web search, however, are not optimized for Open Data and do not address the semantic ambiguity inherent in it. On the other hand, semantic integration is necessary to perform analysis tasks across multiple datasets. To do so in an ad-hoc fashion, however, requires more flexibility and easier integration than most data integration systems provide. It is apparent that an optimal management system for Open Data must combine aspects from both classic approaches. In this article, we propose OPEN, a novel concept for the management and situational analysis of Open Data within a single system. In our approach, we extend a classic database management system, adding support for the identification and dynamic integration of public datasets. As most web users lack the experience and training required to formulate structured queries in a DBMS, we add support for non-expert users to our system, for example though keyword queries. Furthermore, we address the challenge of indexing Open Data

Column-specific Context Extraction for Web Tables

Relational Web tables have become an important resource for applications such as factual search and entity augmentation. A major challenge for an automatic identification of relevant tables on the Web is the fact that many of these tables have missing or non-informative column labels. Research has focused largely on recovering the meaning of columns by inferring class labels from the instances using external knowledge bases. The table context, which often contains additional information on the table's content, is frequently considered as an indicator for the general content of a table, but not as a source for column-specific details. In this paper, we propose a novel approach to identify and extract column-specific information from the context of Web tables. In our extraction framework, we consider different techniques to extract directly as well as indirectly related phrases. We perform a number of experiments on Web tables extracted from Wikipedia. The results show that column-specific information extracted using our simple heuristic significantly boost precision and recall for table and column search