192 research outputs found
Fast Knowledge Graph Completion using Graphics Processing Units
Knowledge graphs can be used in many areas related to data semantics such as
question-answering systems, knowledge based systems. However, the currently
constructed knowledge graphs need to be complemented for better knowledge in
terms of relations. It is called knowledge graph completion. To add new
relations to the existing knowledge graph by using knowledge graph embedding
models, we have to evaluate vector operations, where
is the number of entities and is the number of relation types. It is very
costly.
In this paper, we provide an efficient knowledge graph completion framework
on GPUs to get new relations using knowledge graph embedding vectors. In the
proposed framework, we first define "transformable to a metric space" and then
provide a method to transform the knowledge graph completion problem into the
similarity join problem for a model which is "transformable to a metric space".
After that, to efficiently process the similarity join problem, we derive
formulas using the properties of a metric space. Based on the formulas, we
develop a fast knowledge graph completion algorithm. Finally, we experimentally
show that our framework can efficiently process the knowledge graph completion
problem
Query optimization by using derivability in a data warehouse environment
Materialized summary tables and cached query results are frequently used for the optimization of aggregate queries in a data warehouse. Query rewriting techniques are incorporated into database systems to use those materialized views and thus avoid the access of the possibly huge raw data. A rewriting is only possible if the query is derivable from these views. Several approaches can be found in the literature to check the derivability and find query rewritings. The specific application scenario of a data warehouse with its multidimensional perspective allows the consideration of much more semantic information, e.g. structural dependencies within the dimension hierarchies and different characteristics of measures. The motivation of this article is to use this information to present conditions for derivability in a large number of relevant cases which go beyond previous approaches
Towards a query language for annotation graphs
The multidimensional, heterogeneous, and temporal nature of speech databases
raises interesting challenges for representation and query. Recently,
annotation graphs have been proposed as a general-purpose representational
framework for speech databases. Typical queries on annotation graphs require
path expressions similar to those used in semistructured query languages.
However, the underlying model is rather different from the customary graph
models for semistructured data: the graph is acyclic and unrooted, and both
temporal and inclusion relationships are important. We develop a query language
and describe optimization techniques for an underlying relational
representation.Comment: 8 pages, 10 figure
Middleware-based Database Replication: The Gaps between Theory and Practice
The need for high availability and performance in data management systems has
been fueling a long running interest in database replication from both academia
and industry. However, academic groups often attack replication problems in
isolation, overlooking the need for completeness in their solutions, while
commercial teams take a holistic approach that often misses opportunities for
fundamental innovation. This has created over time a gap between academic
research and industrial practice.
This paper aims to characterize the gap along three axes: performance,
availability, and administration. We build on our own experience developing and
deploying replication systems in commercial and academic settings, as well as
on a large body of prior related work. We sift through representative examples
from the last decade of open-source, academic, and commercial database
replication systems and combine this material with case studies from real
systems deployed at Fortune 500 customers. We propose two agendas, one for
academic research and one for industrial R&D, which we believe can bridge the
gap within 5-10 years. This way, we hope to both motivate and help researchers
in making the theory and practice of middleware-based database replication more
relevant to each other.Comment: 14 pages. Appears in Proc. ACM SIGMOD International Conference on
Management of Data, Vancouver, Canada, June 200
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