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<div class="section" id="module-bsddb">
<h1>12.11. <tt class="xref docutils literal"><span class="pre">bsddb</span></tt> — Interface to Berkeley DB library<a class="headerlink" href="#module-bsddb" title="Permalink to this headline">¶</a></h1>
<p class="deprecated">
<span class="versionmodified">Deprecated since version 2.6: </span>The <tt class="xref docutils literal"><span class="pre">bsddb</span></tt> module has been deprecated for removal in Python 3.0.</p>
<p>The <tt class="xref docutils literal"><span class="pre">bsddb</span></tt> module provides an interface to the Berkeley DB library. Users
can create hash, btree or record based library files using the appropriate open
call. Bsddb objects behave generally like dictionaries. Keys and values must be
strings, however, so to use other objects as keys or to store other kinds of
objects the user must serialize them somehow, typically using
<a title="marshal.dumps" class="reference external" href="marshal.html#marshal.dumps"><tt class="xref docutils literal"><span class="pre">marshal.dumps()</span></tt></a> or <a title="pickle.dumps" class="reference external" href="pickle.html#pickle.dumps"><tt class="xref docutils literal"><span class="pre">pickle.dumps()</span></tt></a>.</p>
<p>The <tt class="xref docutils literal"><span class="pre">bsddb</span></tt> module requires a Berkeley DB library version from 4.0 thru
4.7.</p>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<dl class="last docutils">
<dt><a class="reference external" href="http://www.jcea.es/programacion/pybsddb.htm">http://www.jcea.es/programacion/pybsddb.htm</a></dt>
<dd>The website with documentation for the <tt class="xref docutils literal"><span class="pre">bsddb.db</span></tt> Python Berkeley DB
interface that closely mirrors the object oriented interface provided in
Berkeley DB 4.x itself.</dd>
<dt><a class="reference external" href="http://www.oracle.com/database/berkeley-db/">http://www.oracle.com/database/berkeley-db/</a></dt>
<dd>The Berkeley DB library.</dd>
</dl>
</div>
<p>A more modern DB, DBEnv and DBSequence object interface is available in the
<tt class="xref docutils literal"><span class="pre">bsddb.db</span></tt> module which closely matches the Berkeley DB C API documented at
the above URLs. Additional features provided by the <tt class="xref docutils literal"><span class="pre">bsddb.db</span></tt> API include
fine tuning, transactions, logging, and multiprocess concurrent database access.</p>
<p>The following is a description of the legacy <tt class="xref docutils literal"><span class="pre">bsddb</span></tt> interface compatible
with the old Python bsddb module. Starting in Python 2.5 this interface should
be safe for multithreaded access. The <tt class="xref docutils literal"><span class="pre">bsddb.db</span></tt> API is recommended for
threading users as it provides better control.</p>
<p>The <tt class="xref docutils literal"><span class="pre">bsddb</span></tt> module defines the following functions that create objects that
access the appropriate type of Berkeley DB file. The first two arguments of
each function are the same. For ease of portability, only the first two
arguments should be used in most instances.</p>
<dl class="function">
<dt id="bsddb.hashopen">
<tt class="descclassname">bsddb.</tt><tt class="descname">hashopen</tt><big>(</big><em>filename</em><span class="optional">[</span>, <em>flag</em><span class="optional">[</span>, <em>mode</em><span class="optional">[</span>, <em>pgsize</em><span class="optional">[</span>, <em>ffactor</em><span class="optional">[</span>, <em>nelem</em><span class="optional">[</span>, <em>cachesize</em><span class="optional">[</span>, <em>lorder</em><span class="optional">[</span>, <em>hflags</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#bsddb.hashopen" title="Permalink to this definition">¶</a></dt>
<dd>Open the hash format file named <em>filename</em>. Files never intended to be
preserved on disk may be created by passing <tt class="xref docutils literal"><span class="pre">None</span></tt> as the <em>filename</em>. The
optional <em>flag</em> identifies the mode used to open the file. It may be <tt class="docutils literal"><span class="pre">'r'</span></tt>
(read only), <tt class="docutils literal"><span class="pre">'w'</span></tt> (read-write) , <tt class="docutils literal"><span class="pre">'c'</span></tt> (read-write - create if necessary;
the default) or <tt class="docutils literal"><span class="pre">'n'</span></tt> (read-write - truncate to zero length). The other
arguments are rarely used and are just passed to the low-level <tt class="xref docutils literal"><span class="pre">dbopen()</span></tt>
function. Consult the Berkeley DB documentation for their use and
interpretation.</dd></dl>
<dl class="function">
<dt id="bsddb.btopen">
<tt class="descclassname">bsddb.</tt><tt class="descname">btopen</tt><big>(</big><em>filename</em><span class="optional">[</span>, <em>flag</em><span class="optional">[</span>, <em>mode</em><span class="optional">[</span>, <em>btflags</em><span class="optional">[</span>, <em>cachesize</em><span class="optional">[</span>, <em>maxkeypage</em><span class="optional">[</span>, <em>minkeypage</em><span class="optional">[</span>, <em>pgsize</em><span class="optional">[</span>, <em>lorder</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#bsddb.btopen" title="Permalink to this definition">¶</a></dt>
<dd>Open the btree format file named <em>filename</em>. Files never intended to be
preserved on disk may be created by passing <tt class="xref docutils literal"><span class="pre">None</span></tt> as the <em>filename</em>. The
optional <em>flag</em> identifies the mode used to open the file. It may be <tt class="docutils literal"><span class="pre">'r'</span></tt>
(read only), <tt class="docutils literal"><span class="pre">'w'</span></tt> (read-write), <tt class="docutils literal"><span class="pre">'c'</span></tt> (read-write - create if necessary;
the default) or <tt class="docutils literal"><span class="pre">'n'</span></tt> (read-write - truncate to zero length). The other
arguments are rarely used and are just passed to the low-level dbopen function.
Consult the Berkeley DB documentation for their use and interpretation.</dd></dl>
<dl class="function">
<dt id="bsddb.rnopen">
<tt class="descclassname">bsddb.</tt><tt class="descname">rnopen</tt><big>(</big><em>filename</em><span class="optional">[</span>, <em>flag</em><span class="optional">[</span>, <em>mode</em><span class="optional">[</span>, <em>rnflags</em><span class="optional">[</span>, <em>cachesize</em><span class="optional">[</span>, <em>pgsize</em><span class="optional">[</span>, <em>lorder</em><span class="optional">[</span>, <em>rlen</em><span class="optional">[</span>, <em>delim</em><span class="optional">[</span>, <em>source</em><span class="optional">[</span>, <em>pad</em><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#bsddb.rnopen" title="Permalink to this definition">¶</a></dt>
<dd>Open a DB record format file named <em>filename</em>. Files never intended to be
preserved on disk may be created by passing <tt class="xref docutils literal"><span class="pre">None</span></tt> as the <em>filename</em>. The
optional <em>flag</em> identifies the mode used to open the file. It may be <tt class="docutils literal"><span class="pre">'r'</span></tt>
(read only), <tt class="docutils literal"><span class="pre">'w'</span></tt> (read-write), <tt class="docutils literal"><span class="pre">'c'</span></tt> (read-write - create if necessary;
the default) or <tt class="docutils literal"><span class="pre">'n'</span></tt> (read-write - truncate to zero length). The other
arguments are rarely used and are just passed to the low-level dbopen function.
Consult the Berkeley DB documentation for their use and interpretation.</dd></dl>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p class="last">Beginning in 2.3 some Unix versions of Python may have a <tt class="xref docutils literal"><span class="pre">bsddb185</span></tt> module.
This is present <em>only</em> to allow backwards compatibility with systems which ship
with the old Berkeley DB 1.85 database library. The <tt class="xref docutils literal"><span class="pre">bsddb185</span></tt> module
should never be used directly in new code. The module has been removed in
Python 3.0. If you find you still need it look in PyPI.</p>
</div>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<dl class="last docutils">
<dt>Module <a title="DBM-style interface to the BSD database library." class="reference external" href="dbhash.html#module-dbhash"><tt class="xref docutils literal"><span class="pre">dbhash</span></tt></a></dt>
<dd>DBM-style interface to the <tt class="xref docutils literal"><span class="pre">bsddb</span></tt></dd>
</dl>
</div>
<div class="section" id="hash-btree-and-record-objects">
<span id="bsddb-objects"></span><h2>12.11.1. Hash, BTree and Record Objects<a class="headerlink" href="#hash-btree-and-record-objects" title="Permalink to this headline">¶</a></h2>
<p>Once instantiated, hash, btree and record objects support the same methods as
dictionaries. In addition, they support the methods listed below.</p>
<p class="versionchanged">
<span class="versionmodified">Changed in version 2.3.1: </span>Added dictionary methods.</p>
<dl class="method">
<dt id="bsddb.bsddbobject.close">
<tt class="descclassname">bsddbobject.</tt><tt class="descname">close</tt><big>(</big><big>)</big><a class="headerlink" href="#bsddb.bsddbobject.close" title="Permalink to this definition">¶</a></dt>
<dd>Close the underlying file. The object can no longer be accessed. Since there
is no open <a title="open" class="reference external" href="functions.html#open"><tt class="xref docutils literal"><span class="pre">open()</span></tt></a> method for these objects, to open the file again a new
<tt class="xref docutils literal"><span class="pre">bsddb</span></tt> module open function must be called.</dd></dl>
<dl class="method">
<dt id="bsddb.bsddbobject.keys">
<tt class="descclassname">bsddbobject.</tt><tt class="descname">keys</tt><big>(</big><big>)</big><a class="headerlink" href="#bsddb.bsddbobject.keys" title="Permalink to this definition">¶</a></dt>
<dd>Return the list of keys contained in the DB file. The order of the list is
unspecified and should not be relied on. In particular, the order of the list
returned is different for different file formats.</dd></dl>
<dl class="method">
<dt id="bsddb.bsddbobject.has_key">
<tt class="descclassname">bsddbobject.</tt><tt class="descname">has_key</tt><big>(</big><em>key</em><big>)</big><a class="headerlink" href="#bsddb.bsddbobject.has_key" title="Permalink to this definition">¶</a></dt>
<dd>Return <tt class="docutils literal"><span class="pre">1</span></tt> if the DB file contains the argument as a key.</dd></dl>
<dl class="method">
<dt id="bsddb.bsddbobject.set_location">
<tt class="descclassname">bsddbobject.</tt><tt class="descname">set_location</tt><big>(</big><em>key</em><big>)</big><a class="headerlink" href="#bsddb.bsddbobject.set_location" title="Permalink to this definition">¶</a></dt>
<dd>Set the cursor to the item indicated by <em>key</em> and return a tuple containing the
key and its value. For binary tree databases (opened using <a title="bsddb.btopen" class="reference internal" href="#bsddb.btopen"><tt class="xref docutils literal"><span class="pre">btopen()</span></tt></a>), if
<em>key</em> does not actually exist in the database, the cursor will point to the next
item in sorted order and return that key and value. For other databases,
<a title="exceptions.KeyError" class="reference external" href="exceptions.html#exceptions.KeyError"><tt class="xref docutils literal"><span class="pre">KeyError</span></tt></a> will be raised if <em>key</em> is not found in the database.</dd></dl>
<dl class="method">
<dt id="bsddb.bsddbobject.first">
<tt class="descclassname">bsddbobject.</tt><tt class="descname">first</tt><big>(</big><big>)</big><a class="headerlink" href="#bsddb.bsddbobject.first" title="Permalink to this definition">¶</a></dt>
<dd>Set the cursor to the first item in the DB file and return it. The order of
keys in the file is unspecified, except in the case of B-Tree databases. This
method raises <tt class="xref docutils literal"><span class="pre">bsddb.error</span></tt> if the database is empty.</dd></dl>
<dl class="method">
<dt id="bsddb.bsddbobject.next">
<tt class="descclassname">bsddbobject.</tt><tt class="descname">next</tt><big>(</big><big>)</big><a class="headerlink" href="#bsddb.bsddbobject.next" title="Permalink to this definition">¶</a></dt>
<dd>Set the cursor to the next item in the DB file and return it. The order of
keys in the file is unspecified, except in the case of B-Tree databases.</dd></dl>
<dl class="method">
<dt id="bsddb.bsddbobject.previous">
<tt class="descclassname">bsddbobject.</tt><tt class="descname">previous</tt><big>(</big><big>)</big><a class="headerlink" href="#bsddb.bsddbobject.previous" title="Permalink to this definition">¶</a></dt>
<dd>Set the cursor to the previous item in the DB file and return it. The order of
keys in the file is unspecified, except in the case of B-Tree databases. This
is not supported on hashtable databases (those opened with <a title="bsddb.hashopen" class="reference internal" href="#bsddb.hashopen"><tt class="xref docutils literal"><span class="pre">hashopen()</span></tt></a>).</dd></dl>
<dl class="method">
<dt id="bsddb.bsddbobject.last">
<tt class="descclassname">bsddbobject.</tt><tt class="descname">last</tt><big>(</big><big>)</big><a class="headerlink" href="#bsddb.bsddbobject.last" title="Permalink to this definition">¶</a></dt>
<dd>Set the cursor to the last item in the DB file and return it. The order of keys
in the file is unspecified. This is not supported on hashtable databases (those
opened with <a title="bsddb.hashopen" class="reference internal" href="#bsddb.hashopen"><tt class="xref docutils literal"><span class="pre">hashopen()</span></tt></a>). This method raises <tt class="xref docutils literal"><span class="pre">bsddb.error</span></tt> if the
database is empty.</dd></dl>
<dl class="method">
<dt id="bsddb.bsddbobject.sync">
<tt class="descclassname">bsddbobject.</tt><tt class="descname">sync</tt><big>(</big><big>)</big><a class="headerlink" href="#bsddb.bsddbobject.sync" title="Permalink to this definition">¶</a></dt>
<dd>Synchronize the database on disk.</dd></dl>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">bsddb</span>
<span class="gp">>>> </span><span class="n">db</span> <span class="o">=</span> <span class="n">bsddb</span><span class="o">.</span><span class="n">btopen</span><span class="p">(</span><span class="s">'/tmp/spam.db'</span><span class="p">,</span> <span class="s">'c'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="nb">range</span><span class="p">(</span><span class="mi">10</span><span class="p">):</span> <span class="n">db</span><span class="p">[</span><span class="s">'</span><span class="si">%d</span><span class="s">'</span><span class="o">%</span><span class="n">i</span><span class="p">]</span> <span class="o">=</span> <span class="s">'</span><span class="si">%d</span><span class="s">'</span><span class="o">%</span> <span class="p">(</span><span class="n">i</span><span class="o">*</span><span class="n">i</span><span class="p">)</span>
<span class="gp">...</span>
<span class="gp">>>> </span><span class="n">db</span><span class="p">[</span><span class="s">'3'</span><span class="p">]</span>
<span class="go">'9'</span>
<span class="gp">>>> </span><span class="n">db</span><span class="o">.</span><span class="n">keys</span><span class="p">()</span>
<span class="go">['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']</span>
<span class="gp">>>> </span><span class="n">db</span><span class="o">.</span><span class="n">first</span><span class="p">()</span>
<span class="go">('0', '0')</span>
<span class="gp">>>> </span><span class="n">db</span><span class="o">.</span><span class="n">next</span><span class="p">()</span>
<span class="go">('1', '1')</span>
<span class="gp">>>> </span><span class="n">db</span><span class="o">.</span><span class="n">last</span><span class="p">()</span>
<span class="go">('9', '81')</span>
<span class="gp">>>> </span><span class="n">db</span><span class="o">.</span><span class="n">set_location</span><span class="p">(</span><span class="s">'2'</span><span class="p">)</span>
<span class="go">('2', '4')</span>
<span class="gp">>>> </span><span class="n">db</span><span class="o">.</span><span class="n">previous</span><span class="p">()</span>
<span class="go">('1', '1')</span>
<span class="gp">>>> </span><span class="k">for</span> <span class="n">k</span><span class="p">,</span> <span class="n">v</span> <span class="ow">in</span> <span class="n">db</span><span class="o">.</span><span class="n">iteritems</span><span class="p">():</span>
<span class="gp">... </span> <span class="k">print</span> <span class="n">k</span><span class="p">,</span> <span class="n">v</span>
<span class="go">0 0</span>
<span class="go">1 1</span>
<span class="go">2 4</span>
<span class="go">3 9</span>
<span class="go">4 16</span>
<span class="go">5 25</span>
<span class="go">6 36</span>
<span class="go">7 49</span>
<span class="go">8 64</span>
<span class="go">9 81</span>
<span class="gp">>>> </span><span class="s">'8'</span> <span class="ow">in</span> <span class="n">db</span>
<span class="go">True</span>
<span class="gp">>>> </span><span class="n">db</span><span class="o">.</span><span class="n">sync</span><span class="p">()</span>
<span class="go">0</span>
</pre></div>
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<h3><a href="../contents.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference external" href="#">12.11. <tt class="docutils literal"><span class="pre">bsddb</span></tt> — Interface to Berkeley DB library</a><ul>
<li><a class="reference external" href="#hash-btree-and-record-objects">12.11.1. Hash, BTree and Record Objects</a></li>
</ul>
</li>
</ul>
<h4>Previous topic</h4>
<p class="topless"><a href="dbhash.html"
title="previous chapter">12.10. <tt class="docutils literal"><span class="pre">dbhash</span></tt> — DBM-style interface to the BSD database library</a></p>
<h4>Next topic</h4>
<p class="topless"><a href="dumbdbm.html"
title="next chapter">12.12. <tt class="docutils literal"><span class="pre">dumbdbm</span></tt> — Portable DBM implementation</a></p>
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