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The last part of the model deals with operations on groups (i.e. sets) of 
sequences. The advantage is that this makes it easy to model queries 
involving sequence collections (which is the case in many real-world
situations). All the sequence operators are extended to work with groups 
of similar sequences, instead of with single sequences. This extension
of the SEQ model indicates that a practical implementation of
SEQ would probably involve a nested complex object system.
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</H4>

<hr>
<A NAME="Language"><H2><em> Sequin </em> Query Language</H2></A>
<H4>
<BLOCKQUOTE>
We have devised a query language called <em> Sequin </em> using
which declarative sequence queries can be specified. The language
is similar in flavor to SQL, except that the inputs to queries
as well as the results of queries are sequences. Click 
<!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><!WA20><a href="http://www.cs.wisc.edu/~praveen/projects/sequin.doc"> here </a> for a description of the <em> Sequin </em>
language with examples.
</BLOCKQUOTE>
</H4>

<hr>
<A NAME="Optimization"><H2>Optimization Techniques</H2></A>
<H4>
<BLOCKQUOTE>
We have proposed new optimization techniques for sequence queries 
involving Positional operators. There are existing techniques that
have been proposed for queries with Record-Oriented operators.
Our optimizations use query transformations, meta--data, and caching of 
intermediate results to efficiently evaluate a query. An optimal query 
evaluation plan can be generated using an algorithm that relies on cost 
estimates. One of the important observations is that accessing sequence data 
in a single stream is probably very efficient, and evaluation strategies 
should take this into account.
<p>
The details of the optimization techniques are
described in a published paper (click <!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><!WA21><a href="http://www.cs.wisc.edu/~praveen/papers/seq.sigmod94.ps">here </a>
for postscript version).
</BLOCKQUOTE>
</H4>

<hr>
<A NAME="System"><H2>System Development</H2></A>
<H4>
<BLOCKQUOTE>
The SEQ database system has a client-server
architecture, supporting multiple clients via
a multi-threaded server. The server is built on
top of the <!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><!WA22><a href="http://www.cs.wisc.edu/shore/">SHORE </a> 
storage manager. Both <em> Sequin </em>
and a subset of SQL are supported as query languages
which can be embedded inside each other. The data model
is a nested complex object model that allows arbitrary
levels of nesting of relations inside sequences and vice
versa. The system is also extensible, providing support
for new data types, new ordering domains, user-defined functions, 
new storage implementations and new query languages. For more details
on the SEQ system, click <!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><!WA23><a href="http://www.cs.wisc.edu/~praveen/projects/seqsys.html">here</a>.
</BLOCKQUOTE>
</H4>

<hr>
<A NAME="Publications"><H2>Publications</H2></A>
<BLOCKQUOTE>
<H4>
<!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><!WA24><a href="http://www.cs.wisc.edu/~praveen/papers/seq.sigmod94.ps">
<!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><!WA25><img src="http://www.cs.wisc.edu/~praveen/pics/redball.gif">
Sequence Query Processing </a>

Praveen Seshadri, Miron Livny and Raghu Ramakrishnan.

Proceedings of the <em> ACM SIGMOD Conference on Data Management</em>, May 1994.
<p>

<p>
<!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><!WA26><a href="http://www.cs.wisc.edu/~praveen/papers/seq.de95.ps">
<!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><!WA27><img src="http://www.cs.wisc.edu/~praveen/pics/redball.gif">
SEQ: A Framework for Sequence Data</a>

Praveen Seshadri, Miron Livny and Raghu Ramakrishnan.

Proceedings of the <em> IEEE Conference on Data Engineering</em>, March 1995.
<p>

<p>
<!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><!WA28><a href="http://www.cs.wisc.edu/~praveen/papers/seq.sigmod96.ps">
<!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><!WA29><img src="http://www.cs.wisc.edu/~praveen/pics/redball.gif">
The Design and Implementation of a Sequence Database System</a>

Praveen Seshadri, Miron Livny and Raghu Ramakrishnan.

Submitted to VLDB 96.
<p>

<p>
<!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><!WA30><a href="http://www.cs.wisc.edu/~mcheng/devise/paper2.ps">
<!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><!WA31><img src="http://www.cs.wisc.edu/~praveen/pics/redball.gif">
What's Next? Sequence Queries</a>

Raghu Ramakrishnan, Michael Cheng, Miron Livny, and Praveen Seshadri.

In Proceedings of the <em> International Conference on the Management of Data (COMAD)</em>, 
December, 1994.
<p>
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</H4>

<hr>
<A NAME="Related"><H2>Related Work</H2></A>
<H4>
<BLOCKQUOTE>
The
<!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><!WA32><A HREF="http://www.cs.wisc.edu/~mcheng/devise/devise.html"><B>DEVise</B></A> 
project is complementary to SEQ. It provides a visualization
environment that can be used to explore sequence data. DEVise can act as
a front-end through which queries can be posed against a SEQ database server,
and the answers can be examined graphically.
<p>
Also see:
<UL>
  <LI> <!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><!WA33><A HREF="http://www.cs.wisc.edu/shore/">SHORE Project: Storage Manager used for SEQ</A>
  <LI> <!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><!WA34><A HREF="http://www.cs.wisc.edu/~praveen/projects/people.html">People working on SEQ and related projects</A>
  <LI> <!WA35><!WA35><!WA35><!WA35><!WA35><!WA35><!WA35><!WA35><!WA35><!WA35><!WA35><!WA35><A HREF="http://www.cs.wisc.edu/~kristint/dbmshome.html">UW-Madison, Database Research Group</A>
  <LI> <!WA36><!WA36><!WA36><!WA36><!WA36><!WA36><!WA36><!WA36><!WA36><!WA36><!WA36><!WA36><A HREF="http://www.cs.wisc.edu/">UW-Madison, CS Department Server</A>
</UL>

</BLOCKQUOTE>
</H4>

<hr>
<A NAME="Contacts"><H2>Contact Information</H2></A>
<H4>
<BLOCKQUOTE>

For more information, contact 
<p>
<!WA37><!WA37><!WA37><!WA37><!WA37><!WA37><!WA37><!WA37><!WA37><!WA37><!WA37><!WA37><A HREF="http://www.cs.wisc.edu/~praveen/praveen.html">Praveen Seshadri</A>,
[e-mail]
<p>
<!WA38><!WA38><!WA38><!WA38><!WA38><!WA38><!WA38><!WA38><!WA38><!WA38><!WA38><!WA38><A HREF="http://www.cs.wisc.edu/~raghu/raghu.html">Raghu Ramakrishnan</A>,
[e-mail]
<p>
<!WA39><!WA39><!WA39><!WA39><!WA39><!WA39><!WA39><!WA39><!WA39><!WA39><!WA39><!WA39><A HREF="http://www.cs.wisc.edu/~miron/miron.html">Miron Livny</A>,
[e-mail]
<p>
<ADDRESS>
Computer Sciences Department, <br>
University of Wisconsin, <br>
1210, W.Dayton Street, <br>
Madison, WI 53706.
</ADDRESS>
</BLOCKQUOTE>
</H4>

<HR>
Last modified: Fri Sep 15 1995 by Praveen Seshadri
<ADDRESS>
Praveen Seshadri / [e-mail]
</ADDRESS>


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