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Communications of the ACM

Research Archive


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The Research archive provides access to all Research articles published in past issues of Communications of the ACM.

October 2009


From Communications of the ACM

Distinct-Value Synopses for Multiset Operations

Distinct-Value Synopses for Multiset Operations

The task of estimating the number of distinct values (DVs) in a large dataset arises in a wide variety of settings in computer science and elsewhere. We provide DV estimation techniques for the case in which the dataset of interest…


From Communications of the ACM

Finding the Frequent Items in Streams of Data

Finding the Frequent Items in Streams of Data

Many data generation processes can be modeled as data streams. While this data may be archived and indexed within a data warehouse, it is also important to process the data "as it happens," to provide up to the minute analysis…


From Communications of the ACM

Technical Perspective: Data Stream Processing—When You Only Get One Look

The database and systems communities have made great progress in developing database systems that allow us to store and query huge amounts of data. Real-time analysis is becoming…


From Communications of the ACM

Technical Perspective: Relational Query Optimization—Data Management Meets Statistical Estimation

Relational systems have made it possible to query large collections of data in a declarative style through languages such as SQL. There is a key component that isquery optimizer…

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