<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>DB_ENV->rep_set_config()</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C API Reference" /> <link rel="up" href="rep.html" title="Chapter 10. Replication Methods" /> <link rel="prev" href="repclockskew.html" title="DB_ENV->rep_set_clockskew()" /> <link rel="next" href="repset_limit.html" title="DB_ENV->rep_set_limit()" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 11.2.5.3</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">DB_ENV->rep_set_config()</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="repclockskew.html">Prev</a> </td> <th width="60%" align="center">Chapter 10. Replication Methods </th> <td width="20%" align="right"> <a accesskey="n" href="repset_limit.html">Next</a></td> </tr> </table> <hr /> </div> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="repconfig"></a>DB_ENV->rep_set_config()</h2> </div> </div> </div> <pre class="programlisting">#include <db.h> int DB_ENV->rep_set_config(DB_ENV *env, u_int32_t which, int onoff); </pre> <p> The <code class="methodname">DB_ENV->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 and optionally one or more whitespace characters, and the string "on" or "off". If the optional string is omitted, the default is "on"; for example, "rep_set_config DB_REP_CONF_NOWAIT" or "rep_set_config DB_REP_CONF_NOWAIT on". 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">DB_ENV->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 DB_ENV Handle">DB_ENV</a> handle. </p> <p> The <code class="methodname">DB_ENV->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="DB_ENV->open()">DB_ENV->open()</a> method. This method may also not be called to set master leases after the <a class="xref" href="repstart.html" title="DB_ENV->rep_start()">DB_ENV->rep_start()</a> or <a class="xref" href="repmgrstart.html" title="DB_ENV->repmgr_start()">DB_ENV->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">DB_ENV->rep_set_config()</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="idp54103200"></a>Parameters</h3> </div> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp54044288"></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_AUTOINIT"></a> <code class="literal">DB_REP_CONF_AUTOINIT</code> </p> <p> The replication master will automatically re-initialize outdated clients. This option is turned on by default. </p> </li> <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="DB_ENV->rep_sync()">DB_ENV->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> <li> <p> Replication Manager applications will no longer maintain group membership information persistently on-disk. For more information, see <a href="../../programmer_reference/rep_filename.html" class="olink">Managing Replication Files</a> in the <em class="citetitle">Berkeley DB Programmer's Reference Guide</em>. </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="DB_ENV->open()">DB_ENV->open()</a> method. Its value cannot be changed while the environment is open. All sites in the replication group should have the same value for this configuration flag. </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="DBcursor->get()">DBcursor->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="DB_ENV->repmgr_start()">DB_ENV->repmgr_start()</a> method or the <a class="xref" href="repstart.html" title="DB_ENV->rep_start()">DB_ENV->rep_start()</a> method is called. All sites in the replication group should have the same value for this configuration flag. </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_ELECTIONS"></a> <code class="literal">DB_REPMGR_CONF_ELECTIONS</code> </p> <p> Replication Manager automatically runs elections to choose a new master when the old master appears to have become disconnected. This option is turned on by default. </p> <p> If this option is turned off, the application is responsible for assigning the new master explicitly, by calling the <code class="methodname">DB_ENV->repmgr_start()</code> method. </p> <div class="caution" style="margin-left: 0.5in; margin-right: 0.5in;"> <h3 class="title">Caution</h3> <p> Most Replication Manager applications should accept the default automatic behavior. Allowing two sites in a replication group to act as master simultaneously can lead to loss of data. </p> </div> <p> In an application with multiple processes per database environment, only the main replication process may change this configuration setting. </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_twosite.html" class="olink"> Special considerations for two-site replication groups </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. This option is turned on by default. </p> </li> </ul> </div> </div> <div class="sect3" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h4 class="title"><a id="idp54131888"></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. Most configuration flags are turned off by default, exceptions are noted above. </p> </div> </div> <div class="sect2" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h3 class="title"><a id="idp54111024"></a>Errors</h3> </div> </div> </div> <p> The <code class="methodname">DB_ENV->rep_set_config()</code> <span> <span> method may fail and 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="idp54122464"></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="idp54113984"></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="idp54072160"></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> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="repclockskew.html">Prev</a> </td> <td width="20%" align="center"> <a accesskey="u" href="rep.html">Up</a> </td> <td width="40%" align="right"> <a accesskey="n" href="repset_limit.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DB_ENV->rep_set_clockskew() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DB_ENV->rep_set_limit()</td> </tr> </table> </div> </body> </html>