How to purge the retained MQTT messages?

[flemmingss]

Ref this post from 2019:

Mqtt auto discovery or not

There’s one potential hiccup with MQTT Discovery: a deleted entity might re-appear. The discovery information might be posted to the discovery topic as a retained message. This is useful because it means it is retained (stored) by the MQTT Broker. When Home Assistant is restarted, it re-connects to the MQTT Broker, re-subscribes to the discovery topic and, because the messages are retained, Home Assistant gets them immediately (and the entity is preserved). The potential hiccup is that if you …

How to purge the retained messages?

[sheminasalam]

If you have mqtt issues with tasmota devices, you can effectively clear mqtt retain messages with tasmota device manager. Take a look at this https://github.com/jziolkowski/tdm

And if you have other devices and detailed info check out this http://www.steves-internet-guide.com/mqtt-retained-messages-example/

[sparkydave (🇦🇺 Dave)]

You can also use this:

MQTT Explorer

[123 (Taras)]

You purge a retained message by publishing an empty string to the topic as a retained message. It’s as simple as that.

You can do it directly from Developer tools > Services.

In the following screenshot, we are publishing an empty string (represented by two consecutive single quotes) to the topic your/topic/goes/here/ as a retained message (retain: true).

[brendan]

This is pretty simple, but is there a quick way to bulk purge? I am pretty well looking at this situation now as a device has left 20 odd retained messages in MQTT.
Bit of a pain to purge them one at a time.
I have not found a way to bulk purge yet. Would be nice if there was a wild card to do it.

[123 (Taras)]

@brendan

Bit of a pain to purge them one at a time.

Use an MQTT client like MQTT Explorer. You still have to do it one topic at a time but the task is reduced to simply clicking an icon.

[brendan]

I can do it one topic at a time. Just wish there was a bulk way.

[DavidFW1960 (David)]

There is a bulk way by publishing to the group topic instead of each device

[brendan]

Thanks @DavidFW1960

[123 (Taras)]

What is a “group topic”?

I haven’t seen that term used outside of Tasmota.

[DavidFW1960 (David)]

@123

I haven’t seen that term used outside of Tasmota.

Probably. I only use Tasmota.