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doc: document "child_node..." configuration parameters
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Ian Barwick
@@ -204,7 +204,7 @@
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<listitem>
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<para>
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Every few seconds (defined by the configuration parameter <varname>child_nodes_check_interval</varname>;
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a value of <literal>0</literal> disables this altogether), <application>repmgrd</application> queries
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default: <literal>5</literal> seconds, a value of <literal>0</literal> disables this altogether), <application>repmgrd</application> queries
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the <literal>pg_stat_replication</literal> system view and compares
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the nodes present there against the list of nodes registered with &repmgr; which
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should be attached to the primary.
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@@ -240,7 +240,7 @@
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<filename>repmgr.conf</filename>, <application>repmgrd</application> will then loop through all child nodes.
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If it determines that insufficient child nodes are connected, and a
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minimum of <varname>child_nodes_disconnect_timeout</varname> seconds (default: <literal>30</literal>)
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has elapsed since the last node became disconnected, <application>repmgrd</application> will then execute the
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has elapsed since the last node became disconnected, <application>repmgrd</application> will then execute the
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<varname>child_nodes_disconnect_command</varname> script.
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</para>
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<para>
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@@ -252,16 +252,6 @@
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is connected). Alternatively, if <varname>child_nodes_disconnect_min_count</varname>
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and more than that number of child nodes disconnects, the script will be triggered.
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</para>
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<para>
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The <varname>child_nodes_disconnect_command</varname> script will only be executed once
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while the criteria for its execution are met. If the criteria for its execution are no longer
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met (i.e. some child nodes have reconnected), it will be executed again if
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the criteria for its execution are met again.
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</para>
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<para>
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The <varname>child_nodes_disconnect_command</varname> script will not be executed if
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<application>repmgrd</application> is paused.
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</para>
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</listitem>
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<listitem>
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@@ -285,7 +275,165 @@
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<sect2 id="repmgrd-primary-child-disconnection-configuration">
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<title>Standby disconnections monitoring process configuration</title>
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<para>
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The following parameters, set in <filename>repmgr.conf</filename>,
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control how child node disconnection monitoring operates.
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</para>
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<variablelist>
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<varlistentry>
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<indexterm>
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<primary>child_nodes_check_interval</primary>
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<secondary>child node disconnection monitoring</secondary>
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</indexterm>
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<term><varname>child_nodes_check_interval</varname></term>
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<listitem>
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<para>
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Interval (in seconds) after which <application>repmgrd</application> queries the
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<literal>pg_stat_replication</literal> system view and compares the nodes present
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there against the list of nodes registered with repmgr which should be attached to the primary.
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</para>
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<para>
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Default is <literal>5</literal> seconds, a value of <literal>0</literal> disables this check
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altogether.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<indexterm>
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<primary>child_nodes_disconnect_command</primary>
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<secondary>child node disconnection monitoring</secondary>
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</indexterm>
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<term><varname>child_nodes_disconnect_command</varname></term>
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<listitem>
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<para>
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User-definable script to be executed when <application>repmgrd</application>
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determines that an insufficient number of child nodes are connected. By default
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the script is executed when no child nodes are executed, but the execution
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threshold can be modified by setting one of <varname>child_nodes_connected_min_count</varname>
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or<varname>child_nodes_disconnect_min_count</varname> (see below).
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</para>
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<para>
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The <varname>child_nodes_disconnect_command</varname> script can be
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any user-defined script or program. It <emphasis>must</emphasis> be able
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to be executed by the system user under which the PostgreSQL server itself
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runs (usually <literal>postgres</literal>).
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</para>
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<para>
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If specified, the following format placeholder will be substituted when
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executing <varname>child_nodes_disconnect_command</varname>:
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</para>
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<variablelist>
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<varlistentry>
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<term><option>%p</option></term>
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<listitem>
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<para>
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ID of the node executing the <varname>child_nodes_disconnect_command</varname> script.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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The <varname>child_nodes_disconnect_command</varname> script will only be executed once
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while the criteria for its execution are met. If the criteria for its execution are no longer
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met (i.e. some child nodes have reconnected), it will be executed again if
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the criteria for its execution are met again.
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</para>
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<para>
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The <varname>child_nodes_disconnect_command</varname> script will not be executed if
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<application>repmgrd</application> is <link linkend="repmgrd-pausing">paused</link>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<indexterm>
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<primary>child_nodes_disconnect_timeout</primary>
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<secondary>child node disconnection monitoring</secondary>
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</indexterm>
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<term><varname>child_nodes_disconnect_timeout</varname></term>
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<listitem>
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<para>
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If <application>repmgrd</application> determines that an insufficient number of
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child nodes are connected, it will wait for the specified number of seconds
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to execute the <varname>child_nodes_disconnect_command</varname>.
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</para>
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<para>
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Default: <literal>30</literal> seconds.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<indexterm>
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<primary>child_nodes_connected_min_count</primary>
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<secondary>child node disconnection monitoring</secondary>
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</indexterm>
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<term><varname>child_nodes_connected_min_count</varname></term>
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<listitem>
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<para>
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If the number of child nodes connected falls below the number specified in
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this parameter, the <varname>child_nodes_disconnect_command</varname> script
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will be executed.
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</para>
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<para>
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For example, if <varname>child_nodes_connected_min_count</varname> is set
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to <literal>2</literal>, the <varname>child_nodes_disconnect_command</varname>
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script will be executed if one or no child nodes are connected.
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</para>
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<para>
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Note that <varname>child_nodes_connected_min_count</varname> overrides any value
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set in <varname>child_nodes_disconnect_min_count</varname>.
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</para>
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<para>
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If neither of <varname>child_nodes_connected_min_count</varname> or
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<varname>child_nodes_disconnect_min_count</varname> are set,
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the <varname>child_nodes_disconnect_command</varname> script
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will be executed when no child nodes are connected.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<indexterm>
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<primary>child_nodes_disconnect_min_count</primary>
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<secondary>child node disconnection monitoring</secondary>
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</indexterm>
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<term><varname>child_nodes_disconnect_min_count</varname></term>
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<listitem>
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<para>
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If the number of disconnected child nodes exceeds the number specified in
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this parameter, the <varname>child_nodes_disconnect_command</varname> script
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will be executed.
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</para>
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<para>
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For example, if <varname>child_nodes_disconnect_min_count</varname> is set
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to <literal>2</literal>, the <varname>child_nodes_disconnect_command</varname>
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script will be executed if more than two child nodes are disconnected.
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</para>
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<para>
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Note that any value set in <varname>child_nodes_disconnect_min_count</varname>
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will be overriden by <varname>child_nodes_connected_min_count</varname>.
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</para>
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<para>
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If neither of <varname>child_nodes_connected_min_count</varname> or
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<varname>child_nodes_disconnect_min_count</varname> are set,
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the <varname>child_nodes_disconnect_command</varname> script
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will be executed when no child nodes are connected.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</sect2>
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<sect2 id="repmgrd-primary-child-disconnection-events">
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