# Historical Deadband not working properly

**URL:** <https://forum.inductiveautomation.com/t/historical-deadband-not-working-properly/77270>\
**Category:** Ignition\
**Tags:** perspective\
**Created:** [August 2, 2023, 6:55am UTC](https://forum.inductiveautomation.com/t/historical-deadband-not-working-properly/77270 "2023-08-02T06:55:39Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Learner\_Ignition](https://avatars.discourse-cdn.com/v4/letter/l/b3f665/32.png) [@Learner\_Ignition](https://forum.inductiveautomation.com/u/Learner_Ignition)\
**Post date:** [August 2, 2023, 6:55am UTC](https://forum.inductiveautomation.com/t/historical-deadband-not-working-properly/77270/1 "2023-08-02T06:55:40Z")

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I am using UDT and have memory tag of data type float, and I did the below setting for history to be stored in Mysql database.

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/1/7183abe07c910678f42a77a57a95570f01b3edfa.png)  
However when I change the value from 0 to 1 and from 1 to 2 and from 2 to 3 and from 3 to 5, only 1 gets stored in the database.

![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/8/38f91358967d1612c54771ad20b8ead36d41c8a9.png)  
When I set deadband to 0 and change value all the change in value gets stored in the database, I dont understand whats going on after I put some deadband.

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**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\
**Post date:** [August 2, 2023, 9:14am UTC](https://forum.inductiveautomation.com/t/historical-deadband-not-working-properly/77270/2 "2023-08-02T09:14:20Z")

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Ignition uses compression on the historian to reduce data storage requirements. The two main settings that affect this are `Deadband Style` and `Historical Deadband`. This is explained in the manual.

[https://docs.inductiveautomation.com/display/DOC81/Configuring+Tag+History#ConfiguringTagHistory-DeadbandandAnalogCompression](https://docs.inductiveautomation.com/display/DOC81/Configuring+Tag+History#ConfiguringTagHistory-DeadbandandAnalogCompression)

Note particularly,

> **Auto**  
> The setting will automatically pick either Analog or Discrete, based on the data type of the tag.
> 
> - If the data type of the tag is set to a float or double, then Auto will use the Analog Style.
> - If the data type of the tag is any other type, then the Discrete style will be used.

You might find `Discreet` more easy to work with.

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<div class="post-metadata">

**Author:** ![Learner\_Ignition](https://avatars.discourse-cdn.com/v4/letter/l/b3f665/32.png) [@Learner\_Ignition](https://forum.inductiveautomation.com/u/Learner_Ignition)\
**Post date:** [August 2, 2023, 10:35am UTC](https://forum.inductiveautomation.com/t/historical-deadband-not-working-properly/77270/3 "2023-08-02T10:35:36Z")

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I was having the thoughts that deadband is working like

abs(current value - previous value) \>= deadband ---\> store

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<div class="post-metadata">

**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\
**Post date:** [August 2, 2023, 10:48am UTC](https://forum.inductiveautomation.com/t/historical-deadband-not-working-properly/77270/4 "2023-08-02T10:48:17Z")

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Read the manual carefully. It took me several readings before I grasped how it worked (and even now I'm not sure). I think they have improved the explanation in the 8.1 manual in the link I gave you.

> [@Learner\_Ignition](#):
>
> abs(current value - previous value) \>= deadband ---\> store

It's much more complex than that for "analog".