+ <Plugin mqtt>
+ <Publish "name">
+ Host "mqtt.example.com"
+ Prefix "collectd"
+ </Publish>
+ <Subscribe "name">
+ Host "mqtt.example.com"
+ Topic "collectd/#"
+ </Subscribe>
+ </Plugin>
+
+The plugin's configuration is in B<Publish> and/or B<Subscribe> blocks,
+configuring the sending and receiving direction respectively. The plugin will
+register a write callback named C<mqtt/I<name>> where I<name> is the string
+argument given to the B<Publish> block. Both types of blocks share many but not
+all of the following options. If an option is valid in only one of the blocks,
+it will be mentioned explicitly.
+
+B<Options:>
+
+=over 4
+
+=item B<Host> I<Hostname>
+
+Hostname of the MQTT broker to connect to.
+
+=item B<Port> I<Service>
+
+Port number or service name of the MQTT broker to connect to.
+
+=item B<User> I<UserName>
+
+Username used when authenticating to the MQTT broker.
+
+=item B<Password> I<Password>
+
+Password used when authenticating to the MQTT broker.
+
+=item B<ClientId> I<ClientId>
+
+MQTT client ID to use. Defaults to the hostname used by I<collectd>.
+
+=item B<QoS> [B<0>-B<2>]
+
+Sets the I<Quality of Service>, with the values C<0>, C<1> and C<2> meaning:
+
+=over 4
+
+=item B<0>
+
+At most once
+
+=item B<1>
+
+At least once
+
+=item B<2>
+
+Exactly once
+
+=back
+
+In B<Publish> blocks, this option determines the QoS flag set on outgoing
+messages and defaults to B<0>. In B<Subscribe> blocks, determines the maximum
+QoS setting the client is going to accept and defaults to B<2>. If the QoS flag
+on a message is larger than the maximum accepted QoS of a subscriber, the
+message's QoS will be downgraded.
+
+=item B<Prefix> I<Prefix> (Publish only)
+
+This plugin will use one topic per I<value list> which will looks like a path.
+I<Prefix> is used as the first path element and defaults to B<collectd>.
+
+An example topic name would be:
+
+ collectd/cpu-0/cpu-user
+
+=item B<Retain> B<false>|B<true> (Publish only)
+
+Controls whether the MQTT broker will retain (keep a copy of) the last message
+sent to each topic and deliver it to new subscribers. Defaults to B<false>.
+
+=item B<StoreRates> B<true>|B<false> (Publish only)
+
+Controls whether C<DERIVE> and C<COUNTER> metrics are converted to a I<rate>
+before sending. Defaults to B<true>.
+
+=item B<CleanSession> B<true>|B<false> (Subscribe only)
+
+Controls whether the MQTT "cleans" the session up after the subscriber
+disconnects or if it maintains the subscriber's subscriptions and all messages
+that arrive while the subscriber is disconnected. Defaults to B<true>.
+
+=item B<Topic> I<TopicName> (Subscribe only)
+
+Configures the topic(s) to subscribe to. You can use the single level C<+> and
+multi level C<#> wildcards. Defaults to B<collectd/#>, i.e. all topics beneath
+the B<collectd> branch.
+
+=back
+
+=head2 Plugin C<mysql>
+
+The C<mysql plugin> requires B<mysqlclient> to be installed. It connects to
+one or more databases when started and keeps the connection up as long as
+possible. When the connection is interrupted for whatever reason it will try
+to re-connect. The plugin will complain loudly in case anything goes wrong.
+
+This plugin issues the MySQL C<SHOW STATUS> / C<SHOW GLOBAL STATUS> command
+and collects information about MySQL network traffic, executed statements,
+requests, the query cache and threads by evaluating the
+C<Bytes_{received,sent}>, C<Com_*>, C<Handler_*>, C<Qcache_*> and C<Threads_*>
+return values. Please refer to the B<MySQL reference manual>, I<5.1.6. Server
+Status Variables> for an explanation of these values.
+
+Optionally, master and slave statistics may be collected in a MySQL
+replication setup. In that case, information about the synchronization state
+of the nodes are collected by evaluating the C<Position> return value of the
+C<SHOW MASTER STATUS> command and the C<Seconds_Behind_Master>,
+C<Read_Master_Log_Pos> and C<Exec_Master_Log_Pos> return values of the
+C<SHOW SLAVE STATUS> command. See the B<MySQL reference manual>,
+I<12.5.5.21 SHOW MASTER STATUS Syntax> and
+I<12.5.5.31 SHOW SLAVE STATUS Syntax> for details.
+
+Synopsis: