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<h2 class="title" style="clear: both"><a id="envclose"></a>DB_ENV->close()</h2>
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<pre class="programlisting">#include <db.h>
int
DB_ENV->close(DB_ENV *dbenv, u_int32_t flags); </pre>
<p>
The <code class="methodname">DB_ENV->close()</code> method closes the Berkeley DB environment,
freeing any allocated resources and closing all database handles opened with
this environment handle, as well as closing any underlying subsystems.
</p>
<p>When you call the <code class="methodname">DB_ENV->close()</code> method, all open <a class="link" href="db.html" title="Chapter 2. The DB Handle">DB</a> handles and <a class="link" href="dbc.html" title="Chapter 3. The DBcursor Handle">DBcursor</a>
handles are closed automatically by this function. And, when you close a database handle,
all cursors opened with it are closed automatically.
</p>
<p>
In multiple threads of control, each thread of control opens a database environment and the database handles
within it. When you close each database handle using the <code class="methodname">DB_ENV->close()</code> method, by default, the database is not synchronized and is similar to calling the <code class="methodname">DB->close(DB_NOSYNC)</code> method. This is to avoid
unncessary database synchronization when there are multiple environment handles open.
To ensure all open database handles are synchronized when you close the last environment handle, set the flag parameter value of the <code class="methodname">DB_ENV->close()</code> method to DB_FORCESYNC.
This is similar to calling the <code class="methodname">DB->close(0)</code> method to close each database handle.
</p>
<p>
If a database close operation fails, the method returns a non-zero error value for the first instance of such an error,
and continues to close the rest of the database and environment
handles.
</p>
<p>
The <a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a> handle should
not be closed while any other handle that refers to it is not yet
closed; for example, database environment handles must not be closed
while transactions in the environment
have not yet been committed or aborted. Specifically, this includes the
<a class="link" href="txn.html" title="Chapter 12. The DB_TXN Handle">DB_TXN</a>,
<a class="link" href="logc.html" title="The DB_LOGC Handle">DB_LOGC</a> and
<a class="link" href="memp.html" title="Chapter 8. The DB_MPOOLFILE Handle">DB_MPOOLFILE</a> handles.
</p>
<p>
Where the environment was initialized with the
<a class="link" href="envopen.html#envopen_DB_INIT_LOCK">DB_INIT_LOCK</a> flag,
calling <code class="methodname">DB_ENV->close()</code> does not release any locks still held by the
closing process, providing functionality for long-lived locks.
Processes that want to have all their locks released can do so by
issuing the appropriate <a class="xref" href="lockvec.html" title="DB_ENV->lock_vec()">DB_ENV->lock_vec()</a> call.
</p>
<p>
Where the environment was initialized with the
<a class="link" href="envopen.html#envopen_DB_INIT_MPOOL">DB_INIT_MPOOL</a> flag,
calling <code class="methodname">DB_ENV->close()</code> implies calls to
<a class="xref" href="mempfclose.html" title="DB_MPOOLFILE->close()">DB_MPOOLFILE->close()</a> for any
remaining open files in the memory pool that were returned to this
process by calls to <a class="xref" href="mempfopen.html" title="DB_MPOOLFILE->open()">DB_MPOOLFILE->open()</a>. It does
not imply a call to <a class="xref" href="mempfsync.html" title="DB_MPOOLFILE->sync()">DB_MPOOLFILE->sync()</a> for those
files.
</p>
<p>
Where the environment was initialized with the
<a class="link" href="envopen.html#envopen_DB_INIT_TXN">DB_INIT_TXN</a> flag,
calling <code class="methodname">DB_ENV->close()</code> aborts any unresolved transactions.
Applications should not depend on this behavior for transactions
involving Berkeley DB databases; all such transactions should be
explicitly resolved. The problem with depending on this semantic is
that aborting an unresolved transaction involving database operations
requires a database handle. Because the database handles should have
been closed before calling <code class="methodname">DB_ENV->close()</code>, it will not be possible
to abort the transaction, and recovery will have to be run on the
Berkeley DB environment before further operations are done.
</p>
<p>
Where log cursors were created using the
<a class="xref" href="logcursor.html" title="DB_ENV->log_cursor()">DB_ENV->log_cursor()</a> method,
calling <code class="methodname">DB_ENV->close()</code> does not imply closing those cursors.
</p>
<p>
In multithreaded applications, only a single thread may call the
<code class="methodname">DB_ENV->close()</code> method.
</p>
<p>
After <code class="methodname">DB_ENV->close()</code> has been called, regardless of its return, the
Berkeley DB environment handle may not be accessed again.
</p>
<p>
The <code class="methodname">DB_ENV->close()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp51344960"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp51304968"></a>flags</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>flags</strong></span> parameter must be set to 0
or be set to the following value:
</p>
<p>
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p><a id="dbenvclose_DB_FORCESYNC"></a>
<code class="literal">DB_FORCESYNC</code>
</p>
<p>
When closing each database handle internally,
synchronize the database. If this flag is not specified, the database handle is closed without synchronizing the database.</p>
</li>
</ul>
</div>
<p>
</p>
</div>
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<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp51385496"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DB_ENV Handle">DB_ENV</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp51381384"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="env.html#envlist" title="Database Environments and Related Methods">Database Environments and Related Methods</a>
</p>
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