2,504 research outputs found
Efficient similarity computations on parallel machines using data shaping
Similarity computation is a fundamental operation in all forms of data. Big Data is, typically, characterized by attributes such as volume, velocity, variety, veracity, etc. In general, Big Data variety appears as structured, semi-structured or unstructured forms. The volume of Big Data in general, and semi-structured data in particular, is increasing at a phenomenal rate. Big Data phenomenon is posing new set of challenges to similarity computation problems occurring in semi-structured data.
Technology and processor architecture trends suggest very strongly that future processors shall have ten\u27s of thousands of cores (hardware threads). Another crucial trend is that ratio between on-chip and off-chip memory to core counts is decreasing. State-of-the-art parallel computing platforms such as General Purpose Graphics Processors (GPUs) and MICs are promising for high performance as well high throughput computing. However, processing semi-structured component of Big Data efficiently using parallel computing systems (e.g. GPUs) is challenging. Reason being most of the emerging platforms (e.g. GPUs) are organized as Single Instruction Multiple Thread/Data machines which are highly structured, where several cores (streaming processors) operate in lock-step manner, or they require a high degree of task-level parallelism.
We argue that effective and efficient solutions to key similarity computation problems need to operate in a synergistic manner with the underlying computing hardware. Moreover, semi-structured form input data needs to be shaped or reorganized with the goal to exploit the enormous computing power of \textit{state-of-the-art} highly threaded architectures such as GPUs. For example, shaping input data (via encoding) with minimal data-dependence can facilitate flexible and concurrent computations on high throughput accelerators/co-processors such as GPU, MIC, etc.
We consider various instances of traditional and futuristic problems occurring in intersection of semi-structured data and data analytics. Preprocessing is an operation common at initial stages of data processing pipelines. Typically, the preprocessing involves operations such as data extraction, data selection, etc. In context of semi-structured data, twig filtering is used in identifying (and extracting) data of interest. Duplicate detection and record linkage operations are useful in preprocessing tasks such as data cleaning, data fusion, and also useful in data mining, etc., in order to find similar tree objects. Likewise, tree edit is a fundamental metric used in context of tree problems; and similarity computation between trees another key problem in context of Big Data.
This dissertation makes a case for platform-centric data shaping as a potent mechanism to tackle the data- and architecture-borne issues in context of semi-structured data processing on GPU and GPU-like parallel architecture machines. In this dissertation, we propose several data shaping techniques for tree matching problems occurring in semi-structured data. We experiment with real world datasets. The experimental results obtained reveal that the proposed platform-centric data shaping approach is effective for computing similarities between tree objects using GPGPUs. The techniques proposed result in performance gains up to three orders of magnitude, subject to problem and platform
A Scalable Blocking Framework for Multidatabase Privacy-preserving Record Linkage
Today many application domains, such as national statistics,
healthcare, business analytic, fraud detection, and national
security, require data to be integrated from multiple databases.
Record linkage (RL) is a process used in data integration which
links multiple databases to identify matching records that belong
to the same entity. RL enriches the usefulness of data by
removing duplicates, errors, and inconsistencies which improves
the effectiveness of decision making in data analytic
applications.
Often, organisations are not willing or authorised to share the
sensitive information in their databases with any other party due
to privacy and confidentiality regulations. The linkage of
databases of different organisations is an emerging research area
known as privacy-preserving record linkage (PPRL). PPRL
facilitates the linkage of databases by ensuring the privacy of
the entities in these databases.
In multidatabase (MD) context, PPRL is significantly challenged
by the intrinsic exponential growth in the number of potential
record pair comparisons. Such linkage often requires significant
time and computational resources to produce the resulting
matching sets of records. Due to increased risk of collusion,
preserving the privacy of the data is more problematic with an
increase of number of parties involved in the linkage process.
Blocking is commonly used to scale the linkage of large
databases. The aim of blocking is to remove those record pairs
that correspond to non-matches (refer to different entities).
Many techniques have been proposed for RL and PPRL for blocking
two databases. However, many of these techniques are not suitable
for blocking multiple databases. This creates a need to develop
blocking technique for the multidatabase linkage context as
real-world applications increasingly require more than two
databases.
This thesis is the first to conduct extensive research on
blocking for multidatabase privacy-preserved record linkage
(MD-PPRL). We consider several research problems in blocking of
MD-PPRL. First, we start with a broad background literature on
PPRL. This allow us to identify the main research gaps that need
to be investigated in MD-PPRL. Second, we introduce a blocking
framework for MD-PPRL which provides more flexibility and control
to database owners in the block generation process. Third, we
propose different techniques that are used in our framework for
(1) blocking of multiple databases, (2) identifying blocks that
need to be compared across subgroups of these databases, and (3)
filtering redundant record pair comparisons by the efficient
scheduling of block comparisons to improve the scalability of
MD-PPRL. Each of these techniques covers an important aspect of
blocking in real-world MD-PPRL applications. Finally, this thesis
reports on an extensive evaluation of the combined application of
these methods with real datasets, which illustrates that they
outperform existing approaches in term of scalability, accuracy,
and privacy
Cloud-Scale Entity Resolution: Current State and Open Challenges
Entity resolution (ER) is a process to identify records in information systems, which refer to the same real-world entity. Because in the two recent decades the data volume has grown so large, parallel techniques are called upon to satisfy the ER requirements of high performance and scalability. The development of parallel ER has reached a relatively prosperous stage, and has found its way into several applications. In this work, we first comprehensively survey the state of the art of parallel ER approaches. From the comprehensive overview, we then extract the classification criteria of parallel ER, classify and compare these approaches based on these criteria. Finally, we identify open research questions and challenges and discuss potential solutions and further research potentials in this field
End-to-End Entity Resolution for Big Data: A Survey
One of the most important tasks for improving data quality and the
reliability of data analytics results is Entity Resolution (ER). ER aims to
identify different descriptions that refer to the same real-world entity, and
remains a challenging problem. While previous works have studied specific
aspects of ER (and mostly in traditional settings), in this survey, we provide
for the first time an end-to-end view of modern ER workflows, and of the novel
aspects of entity indexing and matching methods in order to cope with more than
one of the Big Data characteristics simultaneously. We present the basic
concepts, processing steps and execution strategies that have been proposed by
different communities, i.e., database, semantic Web and machine learning, in
order to cope with the loose structuredness, extreme diversity, high speed and
large scale of entity descriptions used by real-world applications. Finally, we
provide a synthetic discussion of the existing approaches, and conclude with a
detailed presentation of open research directions
An Approach to Ad hoc Cloud Computing
We consider how underused computing resources within an enterprise may be
harnessed to improve utilization and create an elastic computing
infrastructure. Most current cloud provision involves a data center model, in
which clusters of machines are dedicated to running cloud infrastructure
software. We propose an additional model, the ad hoc cloud, in which
infrastructure software is distributed over resources harvested from machines
already in existence within an enterprise. In contrast to the data center cloud
model, resource levels are not established a priori, nor are resources
dedicated exclusively to the cloud while in use. A participating machine is not
dedicated to the cloud, but has some other primary purpose such as running
interactive processes for a particular user. We outline the major
implementation challenges and one approach to tackling them
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