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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="chapter" lang="en" id="spi">
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<div class="titlepage">
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<div><div><h2 class="title">
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<a name="spi"></a>Chapter�39.�Server Programming Interface</h2></div></div>
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<p><b>Table of Contents</b></p>
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<dt><span class="sect1"><a href="spi.html#spi-interface">39.1. Interface Functions</a></span></dt>
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<dt><span class="sect1"><a href="spi-interface-support.html">39.2. Interface Support Functions</a></span></dt>
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<dt><span class="sect1"><a href="spi-memory.html">39.3. Memory Management</a></span></dt>
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<dt><span class="sect1"><a href="spi-visibility.html">39.4. Visibility of Data Changes</a></span></dt>
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<dt><span class="sect1"><a href="spi-examples.html">39.5. Examples</a></span></dt>
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<a name="id2654568"></a><p> The <i class="firstterm">Server Programming Interface</i>
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(<span class="acronym">SPI</span>) gives writers of user-defined
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<span class="acronym">C</span> functions the ability to run
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<span class="acronym">SQL</span> commands inside their functions.
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<span class="acronym">SPI</span> is a set of
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interface functions to simplify access to the parser, planner,
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optimizer, and executor. <span class="acronym">SPI</span> also does some
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<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Note</h3>
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<p> The available procedural languages provide various means to
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execute SQL commands from procedures. Some of these are based on or
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modelled after SPI, so this documentation might be of use for users
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of those languages as well.
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<p> To avoid misunderstanding we'll use the term “<span class="quote">function</span>”
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when we speak of <span class="acronym">SPI</span> interface functions and
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“<span class="quote">procedure</span>” for a user-defined C-function that is
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using <span class="acronym">SPI</span>.
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<p> Note that if during the execution of a procedure the transaction is
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aborted because of an error in a command, then control will not be
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returned to your procedure. Rather, all work will be rolled back
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and the server will wait for the next command from the client. A
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related restriction is the inability to execute
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<tt class="command">BEGIN</tt>, <tt class="command">COMMIT</tt>, and
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<tt class="command">ROLLBACK</tt> (transaction control statements) inside
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a procedure. Both of these restrictions will probably be changed in
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<p> <span class="acronym">SPI</span> functions return a nonnegative result on
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success (either via a returned integer value or in the global
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variable <tt class="varname">SPI_result</tt>, as described below). On
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error, a negative result or <tt class="symbol">NULL</tt> will be returned.
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<p> Source code files that use SPI must include the header file
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<tt class="filename">executor/spi.h</tt>.
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<div class="sect1" lang="en"><div class="titlepage">
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<div><div><h2 class="title" style="clear: both">
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<a name="spi-interface"></a>39.1.�Interface Functions</h2></div></div>
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