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<title>Berkeley DB Reference Guide: Building with multiple versions of Berkeley DB</title>
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<td><b><dl><dt>Berkeley DB Reference Guide:<dd>System Installation Notes</dl></b></td>
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<p align=center><b>Building with multiple versions of Berkeley DB</b></p>
<p>In some cases it may be necessary to build applications which include
multiple versions of Berkeley DB.  Examples include applications which include
software from other vendors, or applications running on a system where
the system C library itself uses Berkeley DB.  In such cases, the two versions
of Berkeley DB may be incompatible, that is, they may have different external
and internal interfaces, and may even have different underlying database
formats.</p>
<p>To create a Berkeley DB library whose symbols won't collide with other Berkeley DB
libraries (or other application or library modules, for that matter),
configure Berkeley DB using the <a href="../../ref/build_unix/conf.html#--with-uniquename=NAME">--with-uniquename=NAME</a> configuration option,
and then build Berkeley DB as usual.  (Note that
<a href="../../ref/build_unix/conf.html#--with-uniquename=NAME">--with-uniquename</a> only affects the Berkeley DB C language library build;
loading multiple versions of the C++ or Java APIs will require
additional work.)  The modified symbol names are hidden from the
application in the Berkeley DB header files, that is, there is no need for
the application to be aware that it is using a special library build as
long as it includes the appropriate Berkeley DB header file.</p>
<p>If "NAME" is not specified when configuring with
<a href="../../ref/build_unix/conf.html#--with-uniquename=NAME">--with-uniquename</a>, a default value built from the major and minor
numbers of the Berkeley DB release will be used.  It is rarely necessary to
specify NAME; using the major and minor release numbers will ensure that
only one copy of the library will be loaded into the application unless
two distinct versions really are necessary.</p>
<p>When distributing any library software that uses Berkeley DB, or any software
which will be recompiled by users for their systems, we recommend two
things: First, include the Berkeley DB release as part of your release.  This
will insulate your software from potential Berkeley DB API changes as well as
simplifying your coding because you will only have to code to a single
version of the Berkeley DB API instead of adapting at compile time to whatever
version of Berkeley DB happens to be installed on the target system.  Second,
use <a href="../../ref/build_unix/conf.html#--with-uniquename=NAME">--with-uniquename</a> when configuring Berkeley DB, because that will insure that
you do not unexpectedly collide with other application code or a library
already installed on the target system.</p>
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