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<title>7.13 bsddb -- Interface to Berkeley DB library</title>
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<H1><A NAME="SECTION0091300000000000000000">
7.13 <tt class="module">bsddb</tt> --
         Interface to Berkeley DB library</A>
</H1>

<P>
<A NAME="module-bsddb"></A>
<p class="availability">Availability: <span
 class="platform">Unix, Windows</span>.</p>

<P>
The <tt class="module">bsddb</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 marshal.dumps or pickle.dumps.

<P>
Starting with Python 2.3 the <tt class="module">bsddb</tt> module requires the
Berkeley DB library version 3.2 or later (it is known to work with 3.2
through 4.3 at the time of this writing).

<P>
<div class="seealso">
  <p class="heading">See Also:</p>

  <dl compact="compact" class="seeurl">
    <dt><a href="http://pybsddb.sourceforge.net/"
        class="url">http://pybsddb.sourceforge.net/</a></dt>
    <dd>Website with documentation
  for the new python Berkeley DB interface that closely mirrors the
  sleepycat object oriented interface provided in Berkeley DB 3 and 4.</dd>
  </dl>
  <dl compact="compact" class="seeurl">
    <dt><a href="http://www.sleepycat.com/"
        class="url">http://www.sleepycat.com/</a></dt>
    <dd>Sleepycat Software produces the
  modern Berkeley DB library.</dd>
  </dl>
</div>

<P>
The following is a description of the legacy <tt class="module">bsddb</tt> interface
compatible with the old python bsddb module.  For details about the more
modern Db and DbEnv object oriented interface see the above mentioned
pybsddb URL.

<P>
The <tt class="module">bsddb</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><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2797' xml:id='l2h-2797' class="function">hashopen</tt></b>(</nobr></td>
  <td><var>filename</var><big>[</big><var>, flag</var><big>[</big><var>,
                           mode</var><big>[</big><var>, bsize</var><big>[</big><var>,
                           ffactor</var><big>[</big><var>, nelem</var><big>[</big><var>,
                           cachesize</var><big>[</big><var>, hash</var><big>[</big><var>,
                           lorder</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt>
<dd>
Open the hash format file named <var>filename</var>.  Files never intended
to be preserved on disk may be created by passing <code>None</code> as the
<var>filename</var>.  The optional
<var>flag</var> identifies the mode used to open the file.  It may be
"<tt class="character">r</tt>" (read only), "<tt class="character">w</tt>" (read-write) ,
"<tt class="character">c</tt>" (read-write - create if necessary; the default) or
"<tt class="character">n</tt>" (read-write - truncate to zero length).  The other
arguments are rarely used and are just passed to the low-level
<tt class="cfunction">dbopen()</tt> function.  Consult the Berkeley DB documentation
for their use and interpretation.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2798' xml:id='l2h-2798' class="function">btopen</tt></b>(</nobr></td>
  <td><var>filename</var><big>[</big><var>, flag</var><big>[</big><var>,
mode</var><big>[</big><var>, btflags</var><big>[</big><var>, cachesize</var><big>[</big><var>, maxkeypage</var><big>[</big><var>,
minkeypage</var><big>[</big><var>, pgsize</var><big>[</big><var>, lorder</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt>
<dd>

<P>
Open the btree format file named <var>filename</var>.  Files never intended
to be preserved on disk may be created by passing <code>None</code> as the
<var>filename</var>.  The optional
<var>flag</var> identifies the mode used to open the file.  It may be
"<tt class="character">r</tt>" (read only), "<tt class="character">w</tt>" (read-write),
"<tt class="character">c</tt>" (read-write - create if necessary; the default) or
"<tt class="character">n</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.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2799' xml:id='l2h-2799' class="function">rnopen</tt></b>(</nobr></td>
  <td><var>filename</var><big>[</big><var>, flag</var><big>[</big><var>, mode</var><big>[</big><var>,
rnflags</var><big>[</big><var>, cachesize</var><big>[</big><var>, pgsize</var><big>[</big><var>, lorder</var><big>[</big><var>,
reclen</var><big>[</big><var>, bval</var><big>[</big><var>, bfname</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt>
<dd>

<P>
Open a DB record format file named <var>filename</var>.  Files never intended
to be preserved on disk may be created by passing <code>None</code> as the
<var>filename</var>.  The optional
<var>flag</var> identifies the mode used to open the file.  It may be
"<tt class="character">r</tt>" (read only), "<tt class="character">w</tt>" (read-write),
"<tt class="character">c</tt>" (read-write - create if necessary; the default) or
"<tt class="character">n</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.
</dl>

<P>
<div class="note"><b class="label">Note:</b>
Beginning in 2.3 some Unix versions of Python may have a <tt class="module">bsddb185</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="module">bsddb185</tt> module should never be used directly in new code.
</div>

<P>
<div class="seealso">
  <p class="heading">See Also:</p>

  <dl compact="compact" class="seemodule">
    <dt>Module <b><tt class="module"><a href="module-dbhash.html">dbhash</a></tt>:</b>
    <dd>DBM-style interface to the <tt class="module">bsddb</tt>.
  </dl>
</div>

<P>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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