| Available via | http://dbpubs.stanford.edu/pub/2002-57 |
| Next version(s) |
2003-67 |
|
Submitted on |
22nd of November 2002 |
|
Author |
Arasu, Arvind; Babu, Shivnath; Widom, Jennifer |
|
Title |
An Abstract Semantics and Concrete Language for Continuous Queries over Streams and Relations |
|
Date of publication |
2002 |
|
Citation |
Arasu, Arvind; Babu, Shivnath; Widom, Jennifer. An Abstract Semantics and Concrete Language for Continuous Queries over Streams and Relations |
|
Number of pages |
12 |
|
Language |
English |
|
Project |
STREAM |
|
Type |
Technical Report |
|
Subject group |
Data Streams |
|
Abstract |
Despite the recent surge of research in query processing over data streams, little attention has been devoted to defining precise semantics for continuous queries over streams. We first present an abstract semantics based on several building blocks: formal definitions for streams and relations, mappings among them, and any relational query language. From these basics we define a precise interpretation for continuous queries over streams and relations.
We then propose a concrete language, CQL (for Continuous Query Language), which instantiates the abstract semantics using SQL as the relational query language and window specifications derived from SQL-99 to map from streams to relations. We identify some equivalences that can be used to rewrite CQL queries for optimization, and we discuss some additional implementation issues arising from the language and its semantics. We have implemented a substantial
fraction of
CQL in a Data Stream Management System at Stanford, and we have developed a public repository of
data stream applications that includes a wide variety
of queries expressed in CQL. |
|
Keywords |
Data Streams, Query Language, Semantics, Continuous Queries |
|
Contact address |
arvinda@cs.stanford.edu |
|
Notes |
A short version of this technical report appears in the proceedings of the 9th International Conference
on Data Base Programming Languages (DBPL 2003).
The most recent version this technical report is available on this publications server as
technical report number 2003-67, titled
"The CQL Continuous Query Language: Semantic Foundations and Query Execution", at http://dbpubs.stanford.edu/pub/2003-67. |
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| Management of the document by | rwesley@stanford.edu
| |