History vs Recorder - what's the difference?

I’ve just realised there’s a component called ‘recorder’ that I’ve never enabled, but I’ve always had ‘history’ enabled. If I go to History on the left nav I can see history for 1day, 3days or 1 week. So clearly I’m recording stuff.

So what is Recorder for? The History docs say it depends on Recorder, but I don’t have that in my config. Does it automatically turn on Recorder if you turn on History?

Also my logbook doesn’t show anything. It just has todays date at the top and a spinning indicator. Is that because I’ve not enabled recorder?

Yes. You can enable the recorder explicitly if you want to change its settings.

I am trying to finish wrapping my head around this subject…

I had some issues with overly active sensors (zwave power meter devices) and had to reduce default hassio recording to bring my load averages down (was commonly seeing 2.0+). I did this using the ‘whitelist’ method from the recorder docs (only including what I need).

So far it looks to be working, but to be sure… create an identical include only list for the history component won’t change anything (speed things up)?

The logical side of my brain thinks the recorder would have ultimate say in what is saved in the db, and therefore also have powers over history to decide what history ‘could be’ enabled. Then, history is just a reduced list that the user can use to essentially hide/organize the recorded items that are shown on the history page. Therefore, not adding any history config would mean that the recorder config decides what is recorded, and all of those recorded items will appear in history, correct?

If so, then logically there can be a corner case where an item is enabled in history, but disabled in recorder. What happens then (hopefully just a config warning or simply a blank history graph)?

…or is my line of thinking buggered from the start?

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Thanks, I’m still trying to wrap my head around Recorder too, in hopes of trimming some of the fat out of my database.

This post made me realize I can use the “history” page to help identify which states I don’t care about saving in the DB. Those would be candidates for excluding.

So, I’m giving it a bump in hopes of getting more discussion going.

@truglodite That’s right.

The recorder whitelist/blacklist decides what gets recorded. The history whitelist/blacklist decides what gets displayed.

From the documentation: If any entities are excluded from being recorded, no history will be available for these entities.

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@amelchio

Question; when i include a sensor to the recorder, but exclude it from the history and logbook, does it still shows it’s last known state, in for example a card?

(i know i could try this for myself, but haven’t setup includes/excludes yet, just trying to understand some major parts of HA to figure out the best configuration/setup to start with)