in a two-node cluster configuration, or to quickly restore a

single node in a broken cluster.

</para>

<important>

<para>

If your cluster has more than two nodes, promoting one of the

nodes to the major status can lead to split-brain problems

in case of network failures, and reduce the number of possible

failover options. Consider

<link linkend="setting-up-a-referee">setting up a standalone referee</link>

instead.

</para>

</important>

<para>

To make one of the nodes major, enable the

<literal>multimaster.major_node</literal> parameter on this node:

<programlisting>

ALTER SYSTEM SET multimaster.major_node TO on

ALTER SYSTEM SET multimaster.major_node TO on;

SELECT pg_reload_conf();

</programlisting>

</para>

referee for your cluster, the <varname>major_node</varname>

option is forbidden.

</para>

<important>

<para>

If your cluster has more than two nodes, do not use the major node

setting, as it can lead to split-brain problems

in case of network failures, and reduce the number of possible

failover options. If the major node gets isolated by a network failure

while the majority of nodes are connected to each other, both the major

node and the subset that has a quorum will continue working. Consider

<link linkend="setting-up-a-referee">setting up a standalone referee</link>

instead.

</para>

</important>

</sect4>

</sect3>

</sect2>

</indexterm>

</term>

<listitem>

<para>The node with this flag continues working even if it cannot access the majority of other nodes.

This may be required to break the symmetry in two-node clusters.

<para>The node with this flag continues working even if there is no quorum.

This may be required to break the symmetry in two-node clusters,

or to quickly restore a single node in a broken cluster.

</para>

<important>

<para>This parameter should be used with caution. This parameter can cause the

split-brain problem if you use it on clusters with more than two nodes, or set

it to <literal>true</literal> on more than one node.

Only one node in the cluster can be the major node.

<para>This parameter should be used with caution to avoid split-brain

problems:

<itemizedlist>

<listitem>

<para>

Do not use the <parameter>major_node</> parameter on clusters with more

than two nodes. If the major node gets isolated by a network failure

while the majority of nodes are connected to each other, both the major

node and the subset that has a quorum will continue working.

Consider setting up a standalone referee instead.

</para>

</listitem>

<listitem>

<para>

Never set more than one major node in the cluster.

</para>

</listitem>

</itemizedlist>

</para>

</important>

</listitem>