I’m not a very complicated person and nor is mqttcogs. Data from the mqtt broker is persisted into a single database table. Structure includes an id, topic, utc and payload. That’s pretty much it.
Obviously overtime this table can fill up with data and use up your expensive disc space. Mqtt cogs comes with a very basic setting to allow you to remove data from this table.
You simply choose whether to keep all data or a certain number of days worth of data.
Data is removed twice daily. If you want data to be removed immediately you can deactivate and then activate mqttcogs. This will cause the data pruning to occur immediately.