Conference Proceeding

Reducing metadata complexity for faster table summarization.

01/2010; DOI:10.1145/1739041.1739072 In proceeding of: EDBT 2010, 13th International Conference on Extending Database Technology, Lausanne, Switzerland, March 22-26, 2010, Proceedings
Source: DBLP

ABSTRACT Since the visualization real estate puts stringent constraints on how much data can be presented to the users at once, table summarization is an essential tool in helping users quickly explore large data sets. An effective summary needs to minimize the information loss due to the reduction in details. Summarization algorithms leverage the redundancy in the data to identify value and tuple clustering strategies that represent the (almost) same amount of information with a smaller number of data representatives. It has been shown that, when available, metadata, such as value hierarchies associated to the attributes of the tables, can help greatly reduce the resulting information loss. However, table summarization, whether carried out through data analysis performed on the table from scratch or supported through already available metadata, is an expensive operation. We note that the table summarization process can be significantly sped up when the metadata used for supporting the summarization itself is pre-processed to reduce the unnecessary details. The pre-processing of the metadata, however, needs to be performed carefully to ensure that it does not add significant amounts of additional loss to the table summarization process. In this paper, we propose a tRedux algorithm for value hierarchy pre-processing and reduction. Experimental evaluations show that, depending on the table and taxonomy complexity, metadata summarization can provide gains in table summarization time that can range (in absolute values) from seconds to 10s-of-1000s of seconds. Consequently, while resulting in only an extra ~ 20% reduction in table quality, tRedux can provide ~ 2x speedups in table summarization time. Experiments also show that tRedux has a better performance than alternative metadata reduction strategies in supporting table summarization; and, as the taxonomy complexity increases, the absolute gains of tRedux also increase.

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    ABSTRACT: The Semantic Web (SW) deployment is now a realization and the amount of semantic annotations is ever increasing thanks to several initiatives that promote a change in the current Web towards the Web of Data, where the semantics of data become explicit through data representation formats and standards such as RDF/(S) and OWL. However, such initiatives have not yet been accompanied by efficient intelligent applications that can exploit the implicit semantics and thus, provide more insightful analysis. In this paper, we provide the means for efficiently analyzing and exploring large amounts of semantic data by combining the inference power from the annotation semantics with the analysis capabilities provided by OLAP-style aggregations, navigation, and reporting. We formally present how semantic data should be organized in a well-defined conceptual MD schema, so that sophisticated queries can be expressed and evaluated. Our proposal has been evaluated over a real biomedical scenario, which demonstrates the scalability and applicability of the proposed approach.
    Proceedings of the 2010 EDBT/ICDT Workshops, Lausanne, Switzerland, March 22-26, 2010; 01/2010

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