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ACM Transactions on Database Systems (TODS), Volume 34 Issue 1, April 2009

The design of a query monitoring system
Chaitanya Mishra, Nick Koudas
Article No.: 1
DOI: 10.1145/1508857.1508858

Query monitoring refers to the problem of observing and predicting various parameters related to the execution of a query in a database system. In addition to being a useful tool for database users and administrators, it can also serve as an...

Efficient query processing on graph databases
James Cheng, Yiping Ke, Wilfred Ng
Article No.: 2
DOI: 10.1145/1508857.1508859

We study the problem of processing subgraph queries on a database that consists of a set of graphs. The answer to a subgraph query is the set of graphs in the database that are supergraphs of the query. In this article, we propose an...

TuG synopses for approximate query answering
Joshua Spiegel, Neoklis Polyzotis
Article No.: 3
DOI: 10.1145/1508857.1508860

This article introduces the Tuple Graph (TuG) synopses, a new class of data summaries that enable accurate approximate answers for complex relational queries. The proposed summarization framework adopts a “semi-structured” view of the...

Semantics and implementation of continuous sliding window queries over data streams
Jürgen Krämer, Bernhard Seeger
Article No.: 4
DOI: 10.1145/1508857.1508861

In recent years the processing of continuous queries over potentially infinite data streams has attracted a lot of research attention. We observed that the majority of work addresses individual stream operations and system-related issues rather...

A quality-aware optimizer for information extraction
Alpa Jain, Panagiotis G. Ipeirotis
Article No.: 5
DOI: 10.1145/1508857.1508862

A large amount of structured information is buried in unstructured text. Information extraction systems can extract structured relations from the documents and enable sophisticated, SQL-like queries over unstructured text. Information extraction...

Robust approximate aggregation in sensor data management systems
Jeffrey Considine, Marios Hadjieleftheriou, Feifei Li, John Byers, George Kollios
Article No.: 6
DOI: 10.1145/1508857.1508863

In the emerging area of sensor-based systems, a significant challenge is to develop scalable, fault-tolerant methods to extract useful information from the data the sensors collect. An approach to this data management problem is the use of sensor...

Detecting outlying properties of exceptional objects
Fabrizio Angiulli, Fabio Fassetti, Luigi Palopoli
Article No.: 7
DOI: 10.1145/1508857.1508864

Assume you are given a data population characterized by a certain number of attributes. Assume, moreover, you are provided with the information that one of the individuals in this data population is abnormal, but no reason whatsoever is given to...