ACM Transactions on Database Systems

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 information ...

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 efficient index, FG*...

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 relational ...

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 than the ...

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 systems ...

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 ...

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 you as ...