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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="X-UA-Compatible" content="IE=Edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>11.12. dumbdbm — Portable DBM implementation — Python 2.7.18 documentation</title> <link rel="stylesheet" href="../_static/classic.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script> <script type="text/javascript" src="../_static/jquery.js"></script> <script type="text/javascript" src="../_static/underscore.js"></script> <script type="text/javascript" src="../_static/doctools.js"></script> <script type="text/javascript" src="../_static/language_data.js"></script> <script type="text/javascript" src="../_static/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 2.7.18 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="index" title="Index" href="../genindex.html" /> <link rel="search" title="Search" href="../search.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="next" title="11.13. sqlite3 — DB-API 2.0 interface for SQLite databases" href="sqlite3.html" /> <link rel="prev" title="11.11. bsddb — Interface to Berkeley DB library" href="bsddb.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="file:///usr/share/doc/python2.7/html/library/dumbdbm.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> </head><body> <div id="outdated-warning" style="padding: .5em; text-align: center; background-color: #FFBABA; color: #6A0E0E;"> This document is for an old version of Python that is <a href="https://devguide.python.org/devcycle/#end-of-life-branches">no longer supported</a>. You should install the python3 and python3-doc packages and read the <a href="file:///usr/share/doc/python3-doc/html/library/dumbdbm.html"> Python documentation for the Python3 version packaged in this release</a>. </div> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" accesskey="I">index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="sqlite3.html" title="11.13. sqlite3 — DB-API 2.0 interface for SQLite databases" accesskey="N">next</a> |</li> <li class="right" > <a href="bsddb.html" title="11.11. bsddb — Interface to Berkeley DB library" accesskey="P">previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <a href="../index.html">Python 2.7.18 documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> <li class="nav-item nav-item-2"><a href="persistence.html" accesskey="U">11. Data Persistence</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="module-dumbdbm"> <span id="dumbdbm-portable-dbm-implementation"></span><h1>11.12. <a class="reference internal" href="#module-dumbdbm" title="dumbdbm: Portable implementation of the simple DBM interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dumbdbm</span></code></a> — Portable DBM implementation<a class="headerlink" href="#module-dumbdbm" title="Permalink to this headline">¶</a></h1> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">The <a class="reference internal" href="#module-dumbdbm" title="dumbdbm: Portable implementation of the simple DBM interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dumbdbm</span></code></a> module has been renamed to <code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm.dumb</span></code> in Python 3. The <a class="reference internal" href="../glossary.html#term-2to3"><span class="xref std std-term">2to3</span></a> tool will automatically adapt imports when converting your sources to Python 3.</p> </div> <div class="admonition note" id="index-0"> <p class="first admonition-title">Note</p> <p class="last">The <a class="reference internal" href="#module-dumbdbm" title="dumbdbm: Portable implementation of the simple DBM interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dumbdbm</span></code></a> module is intended as a last resort fallback for the <a class="reference internal" href="anydbm.html#module-anydbm" title="anydbm: Generic interface to DBM-style database modules."><code class="xref py py-mod docutils literal notranslate"><span class="pre">anydbm</span></code></a> module when no more robust module is available. The <a class="reference internal" href="#module-dumbdbm" title="dumbdbm: Portable implementation of the simple DBM interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dumbdbm</span></code></a> module is not written for speed and is not nearly as heavily used as the other database modules.</p> </div> <p>The <a class="reference internal" href="#module-dumbdbm" title="dumbdbm: Portable implementation of the simple DBM interface."><code class="xref py py-mod docutils literal notranslate"><span class="pre">dumbdbm</span></code></a> module provides a persistent dictionary-like interface which is written entirely in Python. Unlike other modules such as <a class="reference internal" href="gdbm.html#module-gdbm" title="gdbm: GNU's reinterpretation of dbm. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">gdbm</span></code></a> and <a class="reference internal" href="bsddb.html#module-bsddb" title="bsddb: Interface to Berkeley DB database library"><code class="xref py py-mod docutils literal notranslate"><span class="pre">bsddb</span></code></a>, no external library is required. As with other persistent mappings, the keys and values must always be strings.</p> <p>The module defines the following:</p> <dl class="exception"> <dt id="dumbdbm.error"> <em class="property">exception </em><code class="descclassname">dumbdbm.</code><code class="descname">error</code><a class="headerlink" href="#dumbdbm.error" title="Permalink to this definition">¶</a></dt> <dd><p>Raised on dumbdbm-specific errors, such as I/O errors. <a class="reference internal" href="exceptions.html#exceptions.KeyError" title="exceptions.KeyError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">KeyError</span></code></a> is raised for general mapping errors like specifying an incorrect key.</p> </dd></dl> <dl class="function"> <dt id="dumbdbm.open"> <code class="descclassname">dumbdbm.</code><code class="descname">open</code><span class="sig-paren">(</span><em>filename</em><span class="optional">[</span>, <em>flag</em><span class="optional">[</span>, <em>mode</em><span class="optional">]</span><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#dumbdbm.open" title="Permalink to this definition">¶</a></dt> <dd><p>Open a dumbdbm database and return a dumbdbm object. The <em>filename</em> argument is the basename of the database file (without any specific extensions). When a dumbdbm database is created, files with <code class="file docutils literal notranslate"><span class="pre">.dat</span></code> and <code class="file docutils literal notranslate"><span class="pre">.dir</span></code> extensions are created.</p> <p>The optional <em>flag</em> argument is currently ignored; the database is always opened for update, and will be created if it does not exist.</p> <p>The optional <em>mode</em> argument is the Unix mode of the file, used only when the database has to be created. It defaults to octal <code class="docutils literal notranslate"><span class="pre">0666</span></code> (and will be modified by the prevailing umask).</p> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 2.2: </span>The <em>mode</em> argument was ignored in earlier versions.</p> </div> </dd></dl> <p>In addition to the dictionary-like methods, <code class="docutils literal notranslate"><span class="pre">dumbdm</span></code> objects provide the following method:</p> <dl class="function"> <dt id="dumbdbm.close"> <code class="descclassname">dumbdbm.</code><code class="descname">close</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dumbdbm.close" title="Permalink to this definition">¶</a></dt> <dd><p>Close the <code class="docutils literal notranslate"><span class="pre">dumbdm</span></code> database.</p> </dd></dl> <div class="admonition seealso"> <p class="first admonition-title">See also</p> <dl class="last docutils"> <dt>Module <a class="reference internal" href="anydbm.html#module-anydbm" title="anydbm: Generic interface to DBM-style database modules."><code class="xref py py-mod docutils literal notranslate"><span class="pre">anydbm</span></code></a></dt> <dd>Generic interface to <code class="docutils literal notranslate"><span class="pre">dbm</span></code>-style databases.</dd> <dt>Module <a class="reference internal" href="dbm.html#module-dbm" title="dbm: The standard "database" interface, based on ndbm. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">dbm</span></code></a></dt> <dd>Similar interface to the DBM/NDBM library.</dd> <dt>Module <a class="reference internal" href="gdbm.html#module-gdbm" title="gdbm: GNU's reinterpretation of dbm. (Unix)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">gdbm</span></code></a></dt> <dd>Similar interface to the GNU GDBM library.</dd> <dt>Module <a class="reference internal" href="shelve.html#module-shelve" title="shelve: Python object persistence."><code class="xref py py-mod docutils literal notranslate"><span class="pre">shelve</span></code></a></dt> <dd>Persistence module which stores non-string data.</dd> <dt>Module <a class="reference internal" href="whichdb.html#module-whichdb" title="whichdb: Guess which DBM-style module created a given database."><code class="xref py py-mod docutils literal notranslate"><span class="pre">whichdb</span></code></a></dt> <dd>Utility module used to determine the type of an existing database.</dd> </dl> </div> <div class="section" id="dumbdbm-objects"> <span id="id1"></span><h2>11.12.1. Dumbdbm Objects<a class="headerlink" href="#dumbdbm-objects" title="Permalink to this headline">¶</a></h2> <p>In addition to the methods provided by the <a class="reference internal" href="userdict.html#UserDict.DictMixin" title="UserDict.DictMixin"><code class="xref py py-class docutils literal notranslate"><span class="pre">UserDict.DictMixin</span></code></a> class, <code class="xref py py-class docutils literal notranslate"><span class="pre">dumbdbm</span></code> objects provide the following methods.</p> <dl class="method"> <dt id="dumbdbm.dumbdbm.sync"> <code class="descclassname">dumbdbm.</code><code class="descname">sync</code><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#dumbdbm.dumbdbm.sync" title="Permalink to this definition">¶</a></dt> <dd><p>Synchronize the on-disk directory and data files. This method is called by the <a class="reference internal" href="#dumbdbm.dumbdbm.sync" title="dumbdbm.dumbdbm.sync"><code class="xref py py-meth docutils literal notranslate"><span class="pre">sync()</span></code></a> method of <code class="xref py py-class docutils literal notranslate"><span class="pre">Shelve</span></code> objects.</p> </dd></dl> </div> </div> </div> </div> </div> <div class="sphinxsidebar" role="navigation" aria-label="main navigation"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table of Contents</a></h3> <ul> <li><a class="reference internal" href="#">11.12. <code class="docutils literal notranslate"><span class="pre">dumbdbm</span></code> — Portable DBM implementation</a><ul> <li><a class="reference internal" href="#dumbdbm-objects">11.12.1. Dumbdbm Objects</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="bsddb.html" title="previous chapter">11.11. <code class="docutils literal notranslate"><span class="pre">bsddb</span></code> — Interface to Berkeley DB library</a></p> <h4>Next topic</h4> <p class="topless"><a href="sqlite3.html" title="next chapter">11.13. <code class="docutils literal notranslate"><span class="pre">sqlite3</span></code> — DB-API 2.0 interface for SQLite databases</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../_sources/library/dumbdbm.rst.txt" rel="nofollow">Show Source</a></li> </ul> </div> <div id="searchbox" style="display: none" role="search"> <h3>Quick search</h3> <div class="searchformwrapper"> <form class="search" action="../search.html" method="get"> <input type="text" name="q" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> </div> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <div class="clearer"></div> </div> <div class="related" role="navigation" aria-label="related navigation"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../py-modindex.html" title="Python Module Index" >modules</a> |</li> <li class="right" > <a href="sqlite3.html" title="11.13. sqlite3 — DB-API 2.0 interface for SQLite databases" >next</a> |</li> <li class="right" > <a href="bsddb.html" title="11.11. bsddb — Interface to Berkeley DB library" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="https://www.python.org/">Python</a> »</li> <li> <a href="../index.html">Python 2.7.18 documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li> <li class="nav-item nav-item-2"><a href="persistence.html" >11. 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