# Easy Chart has data memory when no data exists

**URL:** <https://forum.inductiveautomation.com/t/easy-chart-has-data-memory-when-no-data-exists/5322>\
**Category:** Ignition\
**Created:** [October 24, 2012, 3:16pm UTC](https://forum.inductiveautomation.com/t/easy-chart-has-data-memory-when-no-data-exists/5322 "2012-10-24T15:16:37Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![alanb](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@alanb](https://forum.inductiveautomation.com/u/alanb)\
**Post date:** [October 24, 2012, 3:16pm UTC](https://forum.inductiveautomation.com/t/easy-chart-has-data-memory-when-no-data-exists/5322/1 "2012-10-24T15:16:37Z")

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I’ve seen a weird problem I’m hoping can be explained. I’m putting two analog points in history. The history partition is set to 5 minutes, and the prune age is 15 minutes. The data pruning appears to be working since I do not see many partitions and the time stamps assigned to them are correct.

My problem is with Easy Chart. As seen in the attachment, I have ghost data that does not exist (see bar under time range with red blocks). You will also notice I have selected a time range that encompasses more than one block of data, but only one block is showing data (the latest, with a small blue line near the right-top and red line near right-bottom).

Is there some form of data cache and/or is this a bug?

 ![](https://us1.discourse-cdn.com/inductiveautomation/original/2X/2/25736951d4c2f0597f83f826822fd5b0f6cc8115.PNG)

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**Author:** ![Colby.Clegg](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/colby.clegg/32/3282_2.png) [@Colby.Clegg](https://forum.inductiveautomation.com/u/Colby.Clegg)\
**Post date:** [October 24, 2012, 3:36pm UTC](https://forum.inductiveautomation.com/t/easy-chart-has-data-memory-when-no-data-exists/5322/2 "2012-10-24T15:36:10Z")

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Hi,

It looks like the prune function is not properly clearing out the scan class execution records, which are a piece that fits into how the data histogram is calculated.

These records are stored in the “sqlth\_sce” table. They cover a range, described by “start\_time” and “end\_time”. This [knowledge base](http://www.inductiveautomation.com/support/kb/142) article explains how to get those times into a more readable format. At any rate, take a look at that table, and try deleting some of the older rows to see if that makes a difference. We’ll take a look at it on our side as well.

Regards,

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**Author:** ![alanb](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@alanb](https://forum.inductiveautomation.com/u/alanb)\
**Post date:** [October 24, 2012, 3:41pm UTC](https://forum.inductiveautomation.com/t/easy-chart-has-data-memory-when-no-data-exists/5322/3 "2012-10-24T15:41:31Z")

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I’ll look at it now.

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<div class="post-metadata">

**Author:** ![alanb](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@alanb](https://forum.inductiveautomation.com/u/alanb)\
**Post date:** [October 24, 2012, 4:06pm UTC](https://forum.inductiveautomation.com/t/easy-chart-has-data-memory-when-no-data-exists/5322/4 "2012-10-24T16:06:52Z")

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Deleting some of those records did clean up the histogram.

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**Author:** ![Michael.Stofan](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/michael.stofan/32/3342_2.png) [@Michael.Stofan](https://forum.inductiveautomation.com/u/Michael.Stofan)\
**Post date:** [October 30, 2012, 9:40pm UTC](https://forum.inductiveautomation.com/t/easy-chart-has-data-memory-when-no-data-exists/5322/5 "2012-10-30T21:40:04Z")

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Glad to hear it. We’ll keep working on our end to keep that from happening.