Initializes specific subsystems of the Berkeley DB environment.
</p>
<p>
The syntax of the entry in the <ahref="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG"class="olink">DB_CONFIG</a> is a single line
with the string <codeclass="literal">set_open_flags</code>, one or
more whitespace characters, the method flag parameter as a
string, optionally one or more whitespace characters, and
the string <codeclass="literal">on</code> or <codeclass="literal">off</code>.
If the optional string is omitted, the default is
<codeclass="literal">on</code>; for example,
<codeclass="literal">set_open_flags DB_INIT_REP</code> or
<codeclass="literal">set_open_flags DB_INIT_REP on</code>. Because
the DB_CONFIG file is read when the database environment is
opened, it will silently overrule configuration done before
that time.
</p>
<p>
The method flag parameters are as follows:
</p>
<divclass="itemizedlist">
<ultype="disc">
<li>
DB_INIT_REP
<p>
Enables/disables DB_INIT_REP in the DB_ENV->open method. For example:
This enables region memory allocation from the heap instead of from memory backed by the filesystem or
system shared memory.
This flag implies the environment will only be accessed by a single process (although that
process may be multithreaded). This flag has two effects on the Berkeley DB environment.
First, all underlying data structures are allocated from per-process memory instead of from
shared memory that is accessible to more than a single process. Second, mutexes are only
configured to work between threads.
This setting overwrites the DB_PRIVATE flag passed from the application's DB_ENV->open method.
</p></li>
<li>
DB_THREAD
<p>
Enables/disables DB_THREAD in the DB_ENV->open method. For example:
</p><preclass="programlisting">set_open_flags DB_THREAD on</pre><p>This enables the DB_ENV handle returned by the DB_ENV->open method to be free-threaded; that is, concurrently usable by multiple threads in the address space.
This setting overwrites the DB_THREAD flag passed from the application's DB_ENV->open method.</p></li>
