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253 lines
9.2 KiB
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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>DbSequence::stat()</title>
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<link rel="stylesheet" href="apiReference.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
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<link rel="start" href="index.html" title="Berkeley DB C++ API Reference" />
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<link rel="up" href="seq.html" title="Chapter 12. The DbSequence Handle" />
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<link rel="prev" href="seqset_range.html" title="DbSequence::set_range()" />
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<link rel="next" href="seqstat_print.html" title="DbSequence::stat_print()" />
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</head>
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<body>
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<div xmlns="" class="navheader">
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<div class="libver">
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<p>Library Version 11.2.5.2</p>
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</div>
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">DbSequence::stat()</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="seqset_range.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 12.
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The DbSequence Handle
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="seqstat_print.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="seqstat"></a>DbSequence::stat()</h2>
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</div>
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</div>
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</div>
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<pre class="programlisting">#include <db_cxx.h>
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int
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DbSequence::stat(DB_SEQUENCE_STAT **spp, u_int32_t flags); </pre>
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<p>
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The <code class="methodname">DbSequence::stat()</code> method creates a statistical structure and
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copies a pointer to it into user-specified memory locations.
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Specifically, if <span class="bold"><strong>spp</strong></span> is non-NULL, a
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pointer to the statistics for the database are copied into the memory
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location to which it refers.
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</p>
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<p>
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Statistical structures are stored in allocated memory. If
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application-specific allocation routines have been declared (see
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<a class="xref" href="envset_alloc.html" title="DbEnv::set_alloc()">DbEnv::set_alloc()</a>
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for more information), they are used to allocate the memory;
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otherwise, the standard C library <span class="bold"><strong>malloc</strong></span>(3) is used. The caller is responsible
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for deallocating the memory. To deallocate the memory, free the
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memory reference; references inside the returned memory need not be
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individually freed.
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</p>
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<p>
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In the presence of multiple threads or processes accessing an active
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sequence, the information returned by <code class="methodname">DbSequence::stat()</code> may be
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out-of-date.
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</p>
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<p>
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The <code class="methodname">DbSequence::stat()</code> method cannot be transaction-protected. For
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this reason, it should be called in a thread of control that has no
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open cursors or active transactions.
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</p>
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<p>
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The <code class="methodname">DbSequence::stat()</code> <span>
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<span>
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method either returns a non-zero error value or throws an
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exception that encapsulates a non-zero error value on
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failure, and returns 0 on success.
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</span>
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</span>
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</p>
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<p>
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The statistics are stored in a structure of type <code class="literal">DB_SEQUENCE_STAT</code>.
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The following fields will be filled in:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<p>
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<span class="bold"><strong>int32_t st_cache_size;</strong></span>
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</p>
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<p>
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The number of values that will be cached in this handle.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>db_seq_t st_current;</strong></span>
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</p>
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<p>
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The current value of the sequence in the database.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>u_int32_t st_flags;</strong></span>
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</p>
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<p>
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The flags value for the sequence.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>db_seq_t st_last_value;</strong></span>
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</p>
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<p>
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The last cached value of the sequence.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>db_seq_t st_min;</strong></span>
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</p>
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<p>
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The minimum permitted value of the sequence.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>db_seq_t st_max;</strong></span>
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</p>
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<p>
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The maximum permitted value of the sequence.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>uintmax_t st_nowait;</strong></span>
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</p>
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<p>
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The number of times that a thread of control was able to obtain handle
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mutex without waiting.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>db_seq_t st_value;</strong></span>
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</p>
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<p>
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The current cached value of the sequence.
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</p>
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</li>
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<li>
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<p>
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<span class="bold"><strong>uintmax_t st_wait;</strong></span>
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</p>
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<p>
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The number of times a thread of control was forced to wait on the
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handle mutex.
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</p>
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</li>
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</ul>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3668876"></a>Parameters</h3>
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</div>
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</div>
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</div>
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<div class="sect3" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h4 class="title"><a id="id3669821"></a>flags</h4>
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</div>
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</div>
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</div>
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<p>
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The <span class="bold"><strong>flags</strong></span> parameter must be set by
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bitwise inclusively <span class="bold"><strong>OR</strong></span>'ing together
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one or more of the following values:
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</p>
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<div class="itemizedlist">
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<ul type="disc">
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<li>
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<p>
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<code class="literal">DB_STAT_ALL</code>
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</p>
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<p>
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Display all available information.
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</p>
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</li>
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<li>
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<p>
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<code class="literal">DB_STAT_CLEAR</code>
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</p>
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<p>
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Reset statistics after printing their values.
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</p>
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</li>
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</ul>
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</div>
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</div>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3669249"></a>Class</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="link" href="seq.html" title="Chapter 12. The DbSequence Handle">DbSequence</a>
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</p>
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</div>
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<div class="sect2" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h3 class="title"><a id="id3669730"></a>See Also</h3>
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</div>
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</div>
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</div>
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<p>
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<a class="xref" href="seq.html#seqlist" title="Sequences and Related Methods">Sequences and Related Methods</a>
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</p>
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</div>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="seqset_range.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="seq.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="seqstat_print.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">DbSequence::set_range() </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> DbSequence::stat_print()</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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