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- <!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 V1.79.1" /><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><div xmlns="http://www.w3.org/TR/xhtml1/transitional" 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="46.1. Interface Functions">Up</a></td><th width="60%" align="center">46.1. Interface Functions</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 12.4 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></hr></div><div class="refentry" id="SPI-SPI-CURSOR-OPEN"><div class="titlepage"></div><a id="id-1.8.12.8.16.1" 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">
- Portal SPI_cursor_open(const char * <em class="parameter"><code>name</code></em>, SPIPlanPtr <em class="parameter"><code>plan</code></em>,
- Datum * <em class="parameter"><code>values</code></em>, const char * <em class="parameter"><code>nulls</code></em>,
- bool <em class="parameter"><code>read_only</code></em>)
- </pre></div><div class="refsect1" id="id-1.8.12.8.16.5"><h2>Description</h2><p>
- <code class="function">SPI_cursor_open</code> sets up a cursor (internally,
- a portal) that will execute a statement prepared by
- <code class="function">SPI_prepare</code>. The parameters have the same
- meanings as the corresponding parameters to
- <code class="function">SPI_execute_plan</code>.
- </p><p>
- Using a cursor instead of executing the statement directly has two
- benefits. First, the result rows can be retrieved a few at a time,
- avoiding memory overrun for queries that return many rows. Second,
- a portal can outlive the current C function (it can, in fact, live
- to the end of the current transaction). Returning the portal name
- to the C function's caller provides a way of returning a row set as
- result.
- </p><p>
- The passed-in parameter data will be copied into the cursor's portal, so it
- can be freed while the cursor still exists.
- </p></div><div class="refsect1" id="id-1.8.12.8.16.6"><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>
- name for portal, or <code class="symbol">NULL</code> to let the system
- select a name
- </p></dd><dt><span class="term"><code class="literal">SPIPlanPtr <em class="parameter"><code>plan</code></em></code></span></dt><dd><p>
- prepared statement (returned by <code class="function">SPI_prepare</code>)
- </p></dd><dt><span class="term"><code class="literal">Datum * <em class="parameter"><code>values</code></em></code></span></dt><dd><p>
- An array of actual parameter values. Must have same length as the
- statement's number of arguments.
- </p></dd><dt><span class="term"><code class="literal">const char * <em class="parameter"><code>nulls</code></em></code></span></dt><dd><p>
- An array describing which parameters are null. Must have same length as
- the statement's number of arguments.
- </p><p>
- If <em class="parameter"><code>nulls</code></em> is <code class="symbol">NULL</code> then
- <code class="function">SPI_cursor_open</code> assumes that no parameters
- are null. Otherwise, each entry of the <em class="parameter"><code>nulls</code></em>
- array should be <code class="literal">' '</code> if the corresponding parameter
- value is non-null, or <code class="literal">'n'</code> if the corresponding parameter
- value is null. (In the latter case, the actual value in the
- corresponding <em class="parameter"><code>values</code></em> entry doesn't matter.) Note
- that <em class="parameter"><code>nulls</code></em> is not a text string, just an array:
- it does not need a <code class="literal">'\0'</code> terminator.
- </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-1.8.12.8.16.7"><h2>Return Value</h2><p>
- Pointer to portal containing the cursor. Note there is no error
- return convention; any error will be reported via <code class="function">elog</code>.
- </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">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="spi-interface.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="spi-spi-cursor-open-with-args.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">SPI_execp </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> SPI_cursor_open_with_args</td></tr></table></div></body></html>
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