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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<th colspan="3" align="center">DbEnv::rep_set_config()</th>
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Replication Methods
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<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="repconfig"></a>DbEnv::rep_set_config()</h2>
</div>
</div>
</div>
<pre class="programlisting">#include <db_cxx.h>
int
DbEnv::rep_set_config(u_int32_t which, int onoff); </pre>
<p>
The <code class="methodname">DbEnv::rep_set_config()</code> method configures the Berkeley DB
replication subsystem.
</p>
<p>
The database environment's replication subsystem may also be
configured using the environment's <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file. The
syntax of the entry in that file is a single line with the string
"rep_set_config", one or more whitespace characters, and the method
<span class="bold"><strong>which</strong></span> parameter as a string; for
example, "rep_set_config DB_REP_CONF_NOWAIT". Because the <a href="../../programmer_reference/env_db_config.html#env_db_config.DB_CONFIG" class="olink">DB_CONFIG</a> file is
read when the database environment is opened, it will silently
overrule configuration done before that time.
</p>
<p>
The <code class="methodname">DbEnv::rep_set_config()</code> method configures a database
environment, not only operations performed using the specified
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handle.
</p>
<p>
The <code class="methodname">DbEnv::rep_set_config()</code> method may not be
called to set in-memory replication after the environment is
opened using the
<a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a> method.
This method may also not be called to set master leases after the
<a class="xref" href="repstart.html" title="DbEnv::rep_start()">DbEnv::rep_start()</a> or
<a class="xref" href="repmgrstart.html" title="DbEnv::repmgr_start()">DbEnv::repmgr_start()</a> methods
are called. For all other <span class="bold"><strong>which</strong></span>
parameters, this method may be called at any time during the life
of the application.
</p>
<p>
The <code class="methodname">DbEnv::rep_set_config()</code> <span>
<span>
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1702959"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1702812"></a>onoff</h4>
</div>
</div>
</div>
<p>
If the <span class="bold"><strong>onoff</strong></span> parameter is zero, the
configuration flag is turned off.
Otherwise, it is turned on. All configuration flags are turned off by default.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1703132"></a>which</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>which</strong></span> parameter must be set to
one of the following values:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p><a id="config_DB_REP_CONF_BULK"></a>
<code class="literal">DB_REP_CONF_BULK</code>
</p>
<p>
The replication master sends groups of records to the clients in a
single network transfer.
</p>
</li>
<li>
<p><a id="config_DB_REP_CONF_DELAYCLIENT"></a>
<code class="literal">DB_REP_CONF_DELAYCLIENT</code>
</p>
<p>
The client should delay synchronizing to a newly declared master. Clients configured in this way will remain
unsynchronized until the application calls the
<a class="xref" href="repsync.html" title="DbEnv::rep_sync()">DbEnv::rep_sync()</a> method.
</p>
</li>
<li>
<p><a id="config_DB_REP_CONF_INMEM"></a>
<code class="literal">DB_REP_CONF_INMEM</code>
</p>
<p>
Store internal replication information in memory only.
</p>
<p>
By default, replication creates files in the environment home directory
to preserve some internal information. If this configuration flag is turned
on, replication only stores this internal information in-memory and cannot
keep persistent state across a site crash or reboot. This results in the
following limitations:
</p>
<div class="itemizedlist">
<ul type="circle">
<li>
<p>
A master site should not reappoint itself master
immediately after crashing or rebooting because the application would incur a
slightly higher risk of client crashes. The former master site should rejoin
the replication group as a client. The application should either hold an
election or appoint a different site to be the next master.
</p>
</li>
<li>
<p>
An application has a slightly higher risk that elections will fail or be
unable to complete. Calling additional elections should eventually yield a
winner.
</p>
</li>
<li>
<p>
An application has a slight risk that the wrong site may win an election,
resulting in the loss of some data. This is consistent with the general loss
of data durability when running in-memory.
</p>
</li>
</ul>
</div>
<p>
This configuration flag can only be turned on before the environment
is opened with the <a class="xref" href="envopen.html" title="DbEnv::open()">DbEnv::open()</a>
method. Its value cannot be changed while the environment is open.
</p>
</li>
<li>
<p>
<code class="literal">DB_REP_CONF_LEASE</code>
</p>
<p>
Master leases will be used for this site.
</p>
<p>
Configuring this option may result in
<code class="literal">DB_REP_LEASE_EXPIRED</code> error returns
from the <a class="xref" href="dbget.html" title="Db::get()">Db::get()</a> and
<a class="xref" href="dbcget.html" title="Dbc::get()">Dbc::get()</a> methods
when attempting to read entries from a database after the site's
master lease has expired.
</p>
<p>
This configuration flag may not be set after the
<a class="xref" href="repmgrstart.html" title="DbEnv::repmgr_start()">DbEnv::repmgr_start()</a> method or the
<a class="xref" href="repstart.html" title="DbEnv::rep_start()">DbEnv::rep_start()</a>
method is called.
</p>
</li>
<li>
<p><a id="config_DB_REP_CONF_NOAUTOINIT"></a>
<code class="literal">DB_REP_CONF_NOAUTOINIT</code>
</p>
<p>
The replication master will not automatically re-initialize outdated
clients.
</p>
</li>
<li>
<p><a id="config_DB_REP_CONF_NOWAIT"></a>
<code class="literal">DB_REP_CONF_NOWAIT</code>
</p>
<p>
Berkeley DB method calls that would normally block while clients are
in recovery will return errors immediately.
</p>
</li>
<li>
<p><a id="config_DB_REPMGR_CONF_2SITE_STRICT"></a>
<code class="literal">DB_REPMGR_CONF_2SITE_STRICT</code>
</p>
<p>
Replication Manager observes the strict "majority" rule in managing
elections, even in a group with only 2 sites. This means the client
in a 2-site group will be unable to take over as master if the
original master fails or becomes disconnected. (See the <a href="../../programmer_reference/rep_elect.html" class="olink">Elections</a> section in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em> for more information.) Both sites in the
replication group should have the same value for this configuration flag.
</p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1703201"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbEnv::rep_set_config()</code> <span>
<span>
method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1703489"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
If setting in-memory replication after the database environment is already
opened; if setting master leases after replication is started; if setting
the 2-site strict majority rule for a Base API application;
or if an invalid flag value or parameter was specified.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1703437"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1703033"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="rep.html#replist" title="Replication and Related Methods">Replication and Related Methods</a>
</p>
</div>
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