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<TITLE>The POSTGRES95 User Manual - Introduction</TITLE>
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<A HREF="pg95user.html">[ TOC ]</A>
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<H1>1. INTRODUCTION</H1>
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<HR>
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This document is the user manual for the
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<A HREF="http://s2k-ftp.cs.berkeley.edu:8000/postgres95/"><B>POSTGRES95</B></A>
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database management system developed at the University
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of California at Berkeley. <B>POSTGRES95</B> is based on
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<A HREF="http://s2k-ftp.CS.Berkeley.EDU:8000/postgres/postgres.html">
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<B>POSTGRES release 4.2</B></A>. The POSTGRES project,
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led by Professor Michael Stonebraker, has been sponsored by the
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Defense Advanced Research Projects Agency (DARPA), the
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Army Research Office (ARO), the National Science
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Foundation (NSF), and ESL, Inc.
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<H2>1.1. What is POSTGRES?</H2>
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Traditional relational database management systems
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(DBMSs) support a data model consisting of a collection
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of named relations, containing attributes of a specific
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type. In current commercial systems, possible types
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include floating point numbers, integers, character
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strings, money, and dates. It is commonly recognized
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that this model is inadequate for future data
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processing applications.
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The relational model successfully replaced previous
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models in part because of its "Spartan simplicity".
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However, as mentioned, this simplicity often makes the
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implementation of certain applications very difficult
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to implement. POSTGRES offers substantial additional
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power by incorporating the following four additional
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basic constructs in such a way that users can easily
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extend the system:
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<p>
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<PRE> classes
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inheritance
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types
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functions
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</PRE><p>
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In addition, POSTGRES supports a powerful production
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rule system.
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<H2><A NAME="a-short-history-of-the-postgres-project">1.2. A Short History of the POSTGRES Project</A></H2>
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Implementation of the POSTGRES DBMS began in 1986. The
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initial concepts for the system were presented in
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<A HREF="refs.html#STON86">[STON86]</A> and the definition of the initial data model
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appeared in <A HREF="refs.html#ROW87">[ROWE87]</A>. The design of the rule system at
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that time was described in <A HREF="refs.html#STON87a">[STON87a]</A>. The rationale
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and architecture of the storage manager were detailed
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in <A HREF="refs.html#STON87b">[STON87b]</A>.
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POSTGRES has undergone several major releases since
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then. The first "demoware" system became operational
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in 1987 and was shown at the 1988 <B>ACM-SIGMOD</B>
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Conference. We released Version 1, described in <A HREF="refs.html#STON90a">[STON90a]</A>,
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to a few external users in June 1989. In response to a
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critique of the first rule system <A HREF="refs.html#STON89">[STON89]</A>, the rule
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system was redesigned <A HREF="refs.html#STON90">[STON90b]</A> and Version 2 was
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released in June 1990 with the new rule system.
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Version 3 appeared in 1991 and added support for multiple
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storage managers, an improved query executor, and a
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rewritten rewrite rule system. For the most part,
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releases since then have focused on portability and
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reliability.
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POSTGRES has been used to implement many different
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research and production applications. These include: a
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financial data analysis system, a jet engine
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performance monitoring package, an asteroid tracking
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database, a medical information database, and several
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geographic information systems. POSTGRES has also been
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used as an educational tool at several universities.
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Finally, <A HREF="http://www.illustra.com/">Illustra Information Technologies</A> picked up
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the code and commercialized it.
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POSTGRES became the primary data manager for the
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<A HREF="http://www.sdsc.edu/0/Parts_Collabs/S2K/s2k_home.html">Sequoia 2000</A> scientific computing project in late 1992.
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Furthermore, the size of the external user community
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nearly doubled during 1993. It became increasingly
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obvious that maintenance of the prototype code and
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support was taking up large amounts of time that should
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have been devoted to database research. In an effort
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to reduce this support burden, the project officially
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ended with <B>Version 4.2</B>.
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<H2><A NAME="what-is-postgres95">1.3. What is <B>POSTGRES95</B>?</A></H2>
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<B>POSTGRES95</B> is a derivative of the last official release
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of POSTGRES (version 4.2). The code is now completely
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ANSI C and the code size has been trimmed by 25%. There
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are a lot of internal changes that improve performance
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and code maintainability. <B>POSTGRES95</B> runs about 30-50%
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faster on the Wisconsin Benchmark compared to v4.2.
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Apart from bug fixes, these are the major enhancements:
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<UL>
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<LI>The query language <B>POSTQUEL</B> has been replaced with
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<B>SQL</B> (implemented in the server). We do not support
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subqueries (which can be imitated with user defined
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<B>SQL</B> functions) at the moment. Aggregates have been
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re-implemented. We also added support for <B>GROUP BY</B>.
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The <B>libpq</B> interface is still available for <B>C</B>
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programs.
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<LI>In addition to the monitor program, we provide a new
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program (<B>psql</B>) which supports <B>GNU</B> <B>readline</B>.
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<LI>We added a new front-end library, <B>libpgtcl</B>, that
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supports <B>Tcl</B>-based clients. A sample shell,
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pgtclsh, provides new Tcl commands to interface <B>tcl</B>
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programs with the <B>POSTGRES95</B> backend.
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<LI>The large object interface has been overhauled. We
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kept Inversion large objects as the only mechanism
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for storing large objects. (This is not to be
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confused with the Inversion file system which has been
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removed.)
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<LI>The instance-level rule system has been removed.
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<LI>Rules are still available as rewrite rules.
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<LI>A short tutorial introducing regular <B>SQL</B> features as
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well as those of ours is distributed with the source
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code.
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<LI><B>GNU</B> make (instead of <B>BSD</B> make) is used for the
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build. Also, <B>POSTGRES95</B> can be compiled with an
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unpatched <B>gcc</B> (data alignment of doubles has been
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fixed).
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</UL>
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<p>
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<H2><A NAME="about-this-release">1.4. About This Release</A></H2>
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<B>POSTGRES95</B> is available free of charge. This manual
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describes version 1.0 of <B>POSTGRES95</B>. The authors have
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compiled and tested <B>POSTGRES95</B> on the following
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platforms:
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<p>
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<center>
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<table border=4>
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<tr>
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<th>Architecture</th>
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<th>Processor</th>
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<th>Operating System</th>
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</tr>
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<tr>
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<td>DECstation 3000</td>
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<td>Alpha AXP</td>
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<td>OSF/1 2.1, 3.0, 3.2</td>
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</tr>
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<tr>
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<td>DECstation 5000</td>
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<td>MIPS</td>
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<td>ULTRIX 4.4</td>
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</tr>
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<tr>
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<td>Sun4</td>
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<td>SPARC</td>
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<td>SunOS 4.1.3, 4.1.3_U1; Solaris 2.4</td>
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</tr>
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<tr>
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<td>H-P 9000/700 and 800</td>
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<td>PA-RISC</td>
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<td>HP-UX 9.00, 9.01, 9.03</td>
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</tr>
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<tr>
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<td>Intel</td>
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<td>X86</td>
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<td>Linux 1.2.8, ELF</td>
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</table>
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</center>
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<p>
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<H2><A NAME="outline-of-this-manual">1.5. Outline of This Manual</A></H2>
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From now on, We will use POSTGRES to mean <B>POSTGRES95</B>.
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The first part of this manual goes over some basic sys-
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tem concepts and procedures for starting the POSTGRES
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system. We then turn to a tutorial overview of the
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POSTGRES data model and SQL query language, introducing
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a few of its advanced features. Next, we explain the
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POSTGRES approach to extensibility and describe how
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users can extend POSTGRES by adding user-defined types,
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operators, aggregates, and both query language and pro-
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gramming language functions. After an extremely brief
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overview of the POSTGRES rule system, the manual
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concludes with a detailed appendix that discusses some of
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the more involved and operating system-specific
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procedures involved in extending the system.
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<HR>
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<B>UNIX</B> is a trademark of X/Open, Ltd. Sun4, SPARC, SunOS
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and Solaris are trademarks of Sun Microsystems, Inc. DEC,
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DECstation, Alpha AXP and ULTRIX are trademarks of Digital
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Equipment Corp. PA-RISC and HP-UX are trademarks of
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Hewlett-Packard Co. OSF/1 is a trademark of the Open
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Software Foundation.<p>
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We assume proficiency with UNIX and C programming.
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<HR>
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<font size=-1>
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<A HREF="pg95user.html">[ TOC ]</A>
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[ Previous ]
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