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1<?xml version="1.0" encoding="UTF-8" standalone="no"?>2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>SPI_cursor_open</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="spi-spi-execp.html" title="SPI_execp" /><link rel="next" href="spi-spi-cursor-open-with-args.html" title="SPI_cursor_open_with_args" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">SPI_cursor_open</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="spi-spi-execp.html" title="SPI_execp">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="spi-interface.html" title="47.1. 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Interface Functions</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="spi-spi-cursor-open-with-args.html" title="SPI_cursor_open_with_args">Next</a></td></tr></table><hr /></div><div class="refentry" id="SPI-SPI-CURSOR-OPEN"><div class="titlepage"></div><a id="id-1.8.12.8.19.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">SPI_cursor_open</span></h2><p>SPI_cursor_open — set up a cursor using a statement created with <code class="function">SPI_prepare</code></p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">3Portal SPI_cursor_open(const char * <em class="parameter"><code>name</code></em>, SPIPlanPtr <em class="parameter"><code>plan</code></em>,4 Datum * <em class="parameter"><code>values</code></em>, const char * <em class="parameter"><code>nulls</code></em>,5 bool <em class="parameter"><code>read_only</code></em>)6</pre></div><div class="refsect1" id="id-1.8.12.8.19.5"><h2>Description</h2><p>7 <code class="function">SPI_cursor_open</code> sets up a cursor (internally,8 a portal) that will execute a statement prepared by9 <code class="function">SPI_prepare</code>. The parameters have the same10 meanings as the corresponding parameters to11 <code class="function">SPI_execute_plan</code>.12 </p><p>13 Using a cursor instead of executing the statement directly has two14 benefits. First, the result rows can be retrieved a few at a time,15 avoiding memory overrun for queries that return many rows. Second,16 a portal can outlive the current C function (it can, in fact, live17 to the end of the current transaction). Returning the portal name18 to the C function's caller provides a way of returning a row set as19 result.20 </p><p>21 The passed-in parameter data will be copied into the cursor's portal, so it22 can be freed while the cursor still exists.23 </p></div><div class="refsect1" id="id-1.8.12.8.19.6"><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">const char * <em class="parameter"><code>name</code></em></code></span></dt><dd><p>24 name for portal, or <code class="symbol">NULL</code> to let the system25 select a name26 </p></dd><dt><span class="term"><code class="literal">SPIPlanPtr <em class="parameter"><code>plan</code></em></code></span></dt><dd><p>27 prepared statement (returned by <code class="function">SPI_prepare</code>)28 </p></dd><dt><span class="term"><code class="literal">Datum * <em class="parameter"><code>values</code></em></code></span></dt><dd><p>29 An array of actual parameter values. Must have same length as the30 statement's number of arguments.31 </p></dd><dt><span class="term"><code class="literal">const char * <em class="parameter"><code>nulls</code></em></code></span></dt><dd><p>32 An array describing which parameters are null. Must have same length as33 the statement's number of arguments.34 </p><p>35 If <em class="parameter"><code>nulls</code></em> is <code class="symbol">NULL</code> then36 <code class="function">SPI_cursor_open</code> assumes that no parameters37 are null. Otherwise, each entry of the <em class="parameter"><code>nulls</code></em>38 array should be <code class="literal">' '</code> if the corresponding parameter39 value is non-null, or <code class="literal">'n'</code> if the corresponding parameter40 value is null. (In the latter case, the actual value in the41 corresponding <em class="parameter"><code>values</code></em> entry doesn't matter.) Note42 that <em class="parameter"><code>nulls</code></em> is not a text string, just an array:43 it does not need a <code class="literal">'\0'</code> terminator.44 </p></dd><dt><span class="term"><code class="literal">bool <em class="parameter"><code>read_only</code></em></code></span></dt><dd><p><code class="literal">true</code> for read-only execution</p></dd></dl></div></div><div class="refsect1" id="id-1.8.12.8.19.7"><h2>Return Value</h2><p>45 Pointer to portal containing the cursor. Note there is no error46 return convention; any error will be reported via <code class="function">elog</code>.47 </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="spi-spi-execp.html" title="SPI_execp">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="spi-interface.html" title="47.1. 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