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doc: document "child_node..." configuration parameters

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Ian Barwick
2019-04-24 14:48:38 +09:00
parent 090493ebc9
commit c092ce60a7
1 changed files with 160 additions and 12 deletions
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doc/repmgrd-automatic-failover.sgml
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@@ -204,7 +204,7 @@
<listitem> <listitem>
<para> <para>
Every few seconds (defined by the configuration parameter <varname>child_nodes_check_interval</varname>; Every few seconds (defined by the configuration parameter <varname>child_nodes_check_interval</varname>;
a value of <literal>0</literal> disables this altogether), <application>repmgrd</application> queries default: <literal>5</literal> seconds, a value of <literal>0</literal> disables this altogether), <application>repmgrd</application> queries
the <literal>pg_stat_replication</literal> system view and compares the <literal>pg_stat_replication</literal> system view and compares
the nodes present there against the list of nodes registered with &repmgr; which the nodes present there against the list of nodes registered with &repmgr; which
should be attached to the primary. should be attached to the primary.
@@ -240,7 +240,7 @@
<filename>repmgr.conf</filename>, <application>repmgrd</application> will then loop through all child nodes. <filename>repmgr.conf</filename>, <application>repmgrd</application> will then loop through all child nodes.
If it determines that insufficient child nodes are connected, and a If it determines that insufficient child nodes are connected, and a
minimum of <varname>child_nodes_disconnect_timeout</varname> seconds (default: <literal>30</literal>) minimum of <varname>child_nodes_disconnect_timeout</varname> seconds (default: <literal>30</literal>)
has elapsed since the last node became disconnected, <application>repmgrd</application> will then execute the has elapsed since the last node became disconnected, <application>repmgrd</application> will then execute the
<varname>child_nodes_disconnect_command</varname> script. <varname>child_nodes_disconnect_command</varname> script.
</para> </para>
<para> <para>
@@ -252,16 +252,6 @@
is connected). Alternatively, if <varname>child_nodes_disconnect_min_count</varname> is connected). Alternatively, if <varname>child_nodes_disconnect_min_count</varname>
and more than that number of child nodes disconnects, the script will be triggered. and more than that number of child nodes disconnects, the script will be triggered.
</para> </para>
<para>
The <varname>child_nodes_disconnect_command</varname> script will only be executed once
while the criteria for its execution are met. If the criteria for its execution are no longer
met (i.e. some child nodes have reconnected), it will be executed again if
the criteria for its execution are met again.
</para>
<para>
The <varname>child_nodes_disconnect_command</varname> script will not be executed if
<application>repmgrd</application> is paused.
</para>
</listitem> </listitem>
<listitem> <listitem>
@@ -285,7 +275,165 @@
<sect2 id="repmgrd-primary-child-disconnection-configuration"> <sect2 id="repmgrd-primary-child-disconnection-configuration">
<title>Standby disconnections monitoring process configuration</title> <title>Standby disconnections monitoring process configuration</title>
<para> <para>
The following parameters, set in <filename>repmgr.conf</filename>,
control how child node disconnection monitoring operates.
</para> </para>
<variablelist>
<varlistentry>
<indexterm>
<primary>child_nodes_check_interval</primary>
<secondary>child node disconnection monitoring</secondary>
</indexterm>
<term><varname>child_nodes_check_interval</varname></term>
<listitem>
<para>
Interval (in seconds) after which <application>repmgrd</application> queries the
<literal>pg_stat_replication</literal> system view and compares the nodes present
there against the list of nodes registered with repmgr which should be attached to the primary.
</para>
<para>
Default is <literal>5</literal> seconds, a value of <literal>0</literal> disables this check
altogether.
</para>
</listitem>
</varlistentry>
<varlistentry>
<indexterm>
<primary>child_nodes_disconnect_command</primary>
<secondary>child node disconnection monitoring</secondary>
</indexterm>
<term><varname>child_nodes_disconnect_command</varname></term>
<listitem>
<para>
User-definable script to be executed when <application>repmgrd</application>
determines that an insufficient number of child nodes are connected. By default
the script is executed when no child nodes are executed, but the execution
threshold can be modified by setting one of <varname>child_nodes_connected_min_count</varname>
or<varname>child_nodes_disconnect_min_count</varname> (see below).
</para>
<para>
The <varname>child_nodes_disconnect_command</varname> script can be
any user-defined script or program. It <emphasis>must</emphasis> be able
to be executed by the system user under which the PostgreSQL server itself
runs (usually <literal>postgres</literal>).
</para>
<para>
If specified, the following format placeholder will be substituted when
executing <varname>child_nodes_disconnect_command</varname>:
</para>
<variablelist>
<varlistentry>
<term><option>%p</option></term>
<listitem>
<para>
ID of the node executing the <varname>child_nodes_disconnect_command</varname> script.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
The <varname>child_nodes_disconnect_command</varname> script will only be executed once
while the criteria for its execution are met. If the criteria for its execution are no longer
met (i.e. some child nodes have reconnected), it will be executed again if
the criteria for its execution are met again.
</para>
<para>
The <varname>child_nodes_disconnect_command</varname> script will not be executed if
<application>repmgrd</application> is <link linkend="repmgrd-pausing">paused</link>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<indexterm>
<primary>child_nodes_disconnect_timeout</primary>
<secondary>child node disconnection monitoring</secondary>
</indexterm>
<term><varname>child_nodes_disconnect_timeout</varname></term>
<listitem>
<para>
If <application>repmgrd</application> determines that an insufficient number of
child nodes are connected, it will wait for the specified number of seconds
to execute the <varname>child_nodes_disconnect_command</varname>.
</para>
<para>
Default: <literal>30</literal> seconds.
</para>
</listitem>
</varlistentry>
<varlistentry>
<indexterm>
<primary>child_nodes_connected_min_count</primary>
<secondary>child node disconnection monitoring</secondary>
</indexterm>
<term><varname>child_nodes_connected_min_count</varname></term>
<listitem>
<para>
If the number of child nodes connected falls below the number specified in
this parameter, the <varname>child_nodes_disconnect_command</varname> script
will be executed.
</para>
<para>
For example, if <varname>child_nodes_connected_min_count</varname> is set
to <literal>2</literal>, the <varname>child_nodes_disconnect_command</varname>
script will be executed if one or no child nodes are connected.
</para>
<para>
Note that <varname>child_nodes_connected_min_count</varname> overrides any value
set in <varname>child_nodes_disconnect_min_count</varname>.
</para>
<para>
If neither of <varname>child_nodes_connected_min_count</varname> or
<varname>child_nodes_disconnect_min_count</varname> are set,
the <varname>child_nodes_disconnect_command</varname> script
will be executed when no child nodes are connected.
</para>
</listitem>
</varlistentry>
<varlistentry>
<indexterm>
<primary>child_nodes_disconnect_min_count</primary>
<secondary>child node disconnection monitoring</secondary>
</indexterm>
<term><varname>child_nodes_disconnect_min_count</varname></term>
<listitem>
<para>
If the number of disconnected child nodes exceeds the number specified in
this parameter, the <varname>child_nodes_disconnect_command</varname> script
will be executed.
</para>
<para>
For example, if <varname>child_nodes_disconnect_min_count</varname> is set
to <literal>2</literal>, the <varname>child_nodes_disconnect_command</varname>
script will be executed if more than two child nodes are disconnected.
</para>
<para>
Note that any value set in <varname>child_nodes_disconnect_min_count</varname>
will be overriden by <varname>child_nodes_connected_min_count</varname>.
</para>
<para>
If neither of <varname>child_nodes_connected_min_count</varname> or
<varname>child_nodes_disconnect_min_count</varname> are set,
the <varname>child_nodes_disconnect_command</varname> script
will be executed when no child nodes are connected.
</para>
</listitem>
</varlistentry>
</variablelist>
</sect2> </sect2>
<sect2 id="repmgrd-primary-child-disconnection-events"> <sect2 id="repmgrd-primary-child-disconnection-events">