Powerful SQL:2003 extensions [1] for querying complex events were
recently proposed by an ANSI working group in which DBMS vendors
and data stream management systems (DSMS) startup companies joined
forces. This presentation will provide an introduction and
in-depth analysis of the proposed specs--which should be discussed
at the workshop since they (i) will impact research directions and
commercial systems, and (ii) raise issues on semantics, expressive
power, and query optimization that should be discussed in this
experts' forum. The proposed ANSI specs are largely based on
SQL-TS [2], which proposed (1) a sequence pattern language for
time series, based on regular expressions for describing composite
events, and (2) query optimization techniques based on a
generalization of the Knuth, Morris & Pratt string-search
algorithm. The newly proposed ANSI specs [1] add several
extensions--including constructs to support disjunctive patterns
and others that entail finer control on the answers returned by
queries. Through various examples, this presentation will
illustrate the main constructs proposed in [2], their power in
expressing complex event queries, and the semantic and
optimization issues raise by these constructs.
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[1] Zemke, Andrew Witkowski, Mitch Cherniak, Latha Colby:
Pattern matching in sequences of rows--ISO/IEC JTC1/SC3
ANSI NCITS H2-2006-nnn, Change Proposal, March 2, 2007.
[2] Reza Sadri, Carlo Zaniolo, Amir M. Zarkesh, Jafar Adibi:
Expressing and optimizing sequence queries in database
systems, ACM Transactions on database systems, Vol 29, No. 2, June
2004, pages 282-318.