mirror of
https://github.com/yasuhirokimura/db18
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Yasuhiro KIMURA
244 lines
8.6 KiB
HTML
244 lines
8.6 KiB
HTML
<?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>Dbc::db_stream()</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="blob.html" title="Chapter 14. External Files" />
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<link rel="prev" href="set_blob_threshold.html" title="Db::set_ext_file_threshold()" />
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<link rel="next" href="dbstream_close.html" title="DbStream::close()" />
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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 18.1.40</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">
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<span xmlns="http://www.w3.org/1999/xhtml">Dbc::db_stream()</span>
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</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="set_blob_threshold.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 14.
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External Files
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</th>
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<td width="20%" align="right"> <a accesskey="n" href="dbstream_close.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="dbstream"></a>
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<span>Dbc::db_stream()</span>
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</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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Dbc::db_stream(DbStream **dbs, u_int32_t flags); </pre>
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<p>
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The <code class="methodname">Dbc::db_stream()</code> method points to a
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key/value pair where the data item is an external file.
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Use the <span class="bold"><strong>flags</strong></span> parameter
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to indicate whether the stream is to be opened for reading, or for
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reading and writing.
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</p>
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<p>
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Once the stream is opened, you read it using <a class="xref" href="dbstream_read.html" title="DbStream::read()">
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<span>DbStream::read()</span>
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</a>, and
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you write to it using <a class="xref" href="dbstream_write.html" title="DbStream::write()">
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<span>DbStream::write()</span>
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</a>.
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</p>
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<p>
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Close this stream using <a class="xref" href="dbstream_close.html" title="DbStream::close()">
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<span>DbStream::close()</span>
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</a>.
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</p>
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<p>
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If the data item is not an external file, this method returns an
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error.
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</p>
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<p>
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Unless otherwise specified, the
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<code class="methodname">Dbc::db_stream()</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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<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="idm139755608737872"></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="idm139755608736928"></a>dbs</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>dbs</strong></span>
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parameter references memory into which is copied the newly
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opened stream.
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</p>
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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="idm139755608780976"></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
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must be set by bitwise inclusively
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<span class="bold"><strong>OR</strong></span>'ing together one or more
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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><a id="blobs_DB_STREAM_READ"></a>
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<code class="literal">DB_STREAM_READ</code>
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</p>
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<p>
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Indicates that the stream is to be opened for
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read-only access.
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</p>
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</li>
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<li>
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<p><a id="blobs_DB_STREAM_WRITE"></a>
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<code class="literal">DB_STREAM_WRITE</code>
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</p>
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<p>
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Indicates that the stream is to be opened for
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read write access. The stream is sync'd to disc when
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the stream is closed.
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</p>
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</li>
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<li>
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<p><a id="blobs_DB_STREAM_SYNC_WRITE"></a>
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<code class="literal">DB_STREAM_SYNC_WRITE</code>
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</p>
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<p>
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Indicates that the stream is to be opened for
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read and write access. The stream is sync'd to disc
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after each write, instead of when the stream is closed.
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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="idm139755608725024"></a>Errors</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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The <code class="methodname">Dbc::db_stream()</code> <span>
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<span>
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method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
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exception, encapsulating one of the following non-zero errors, or return one
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of the following non-zero errors:
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</span>
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</span>
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</p>
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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="idm139755608704880"></a>EINVAL</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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If the data item is not an external file; or if an invalid flag
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or parameter is specified.
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</p>
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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="idm139755608707792"></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="dbc.html" title="Chapter 3. The Dbc Handle">Dbc</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="idm139755608714112"></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="blob.html#bloblist" title="External Files and Related Methods">External Files 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="set_blob_threshold.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="blob.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="dbstream_close.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">
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<span>Db::set_ext_file_threshold()</span>
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</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">
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<span>DbStream::close()</span>
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</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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