# Bad values in tag history

**URL:** <https://forum.inductiveautomation.com/t/bad-values-in-tag-history/10777>\
**Category:** Ignition\
**Created:** [November 12, 2015, 8:51am UTC](https://forum.inductiveautomation.com/t/bad-values-in-tag-history/10777 "2015-11-12T08:51:34Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Serhii](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Serhii](https://forum.inductiveautomation.com/u/Serhii)\
**Post date:** [November 12, 2015, 8:51am UTC](https://forum.inductiveautomation.com/t/bad-values-in-tag-history/10777/1 "2015-11-12T08:51:34Z")

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Hi!  
Sometimes I have bad values stores in MySQL and I don’t know how I got it…  
[screenshot.su/show.php?img=4c4b5 … 4cbd8c.jpg](http://screenshot.su/show.php?img=4c4b57e53d59b1ac7dd1c400cc4cbd8c.jpg)

1. How can I know why it happens?
2. How to delete this bad values from tag history?
3. How to limit records if I got values like this?

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [November 12, 2015, 1:07pm UTC](https://forum.inductiveautomation.com/t/bad-values-in-tag-history/10777/2 "2015-11-12T13:07:41Z")

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What’s bad about them? They are very close to zero, but otherwise valid floating point values.

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<div class="post-metadata">

**Author:** ![Serhii](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Serhii](https://forum.inductiveautomation.com/u/Serhii)\
**Post date:** [November 12, 2015, 1:24pm UTC](https://forum.inductiveautomation.com/t/bad-values-in-tag-history/10777/3 "2015-11-12T13:24:48Z")

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The can’t be so low or so high…  
Should be from 0 to 10000.

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**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [November 12, 2015, 1:46pm UTC](https://forum.inductiveautomation.com/t/bad-values-in-tag-history/10777/4 "2015-11-12T13:46:13Z")

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Floating point values can have round-off issues – unavoidably. The number you circled is -0.0000000006959. That’s zero for most purposes. Add deliberate rounding (in the PLC, probably) to the appropriate number of decimal places if that’s a problem.

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<div class="post-metadata">

**Author:** ![Serhii](https://avatars.discourse-cdn.com/v4/letter/s/df788c/32.png) [@Serhii](https://forum.inductiveautomation.com/u/Serhii)\
**Post date:** [January 12, 2016, 2:52pm UTC](https://forum.inductiveautomation.com/t/bad-values-in-tag-history/10777/5 "2016-01-12T14:52:18Z")

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But how to delete these values?