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The Design and Implementation of a Sequence Database System *

The Internet is a loosely coupled federation of computer servers and clients. Clients are sometime disconnected, and yet they need to be able continue functioning. Rather than building tightly- coupled RPC-based applications, Internet-scale applications must be constructed as asynchronous tasks structured as workflows involving multiple autonomous agents. eMail gives an intuitive understanding of these design issues. You want to be able to read and send mail. | The Design and Implementation of a Sequence Database System Praveen Seshadri Miron Livny Computer Sciences Department U.Wisconsin Madison WI53706 pra veen miron raghu @cs. wisc.edu Raghu Ramakrishnan Abstract This paper discusses the design and implementation of SEQ a database system with support for sequence data. SEQ models a sequence as an ordered collection of records and supports a declarative sequence query language based on an algebra of query operators thereby permitting algebraic query optimization and evaluation. SEQ has been built as a component of the PREDATOR database system that provides support for relational and other kinds of complex data as well. There are three distinct contributions made in this paper. 1 We describe the specification of sequence queries using the S QlẢĩN query language. 2 We quantitatively demonstrate the importance of various storage and optimization techniques by studying their effect on performance. 3 We present a novel nested design paradigm used in PREDATOR to combine sequence and relational data. 1 Introduction Much real-life information contains logical ordering relationships between data items. Sequence data refers to data that is ordered due to such a relationship. Traditional relational databases provide no abstraction of ordering in the data model and do not support queries based on the logical sequentiality in the data. In earlier work we had described a data model Praveen Seshadri was supported by IBM Research Grant 93-F153900-000 and an IBM Cooperative Fellowship. Miron Livny and Raghu Ramakrishnan were supported by NASA Research Grant NAGW-3921. Raghu Ramakrish-nan was also supported by a Packard Foundation Fellowship in Science and Engineering a Presidential Young Investigator Award with matching grants from DEC Tandem and Xerox and NSF grant IRI-9011563. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage the