Deletion of Historical Data

This guide explains how to permanently remove incorrect or unwanted historical values from a datapoint — for example, a single erroneous spike caused by a sensor glitch that doesn't reflect the surrounding trend.

Warning: Deleting historical data from the database is permanent and cannot be undone. Always double-check your selection before confirming, and make sure you understand the difference between removing data from the web display only versus permanently deleting it from the database (see Step 2 below).

Deleting historical data requires elevated project permissions — this is not available to standard users by default.

1. In the Mervis Portal, go to your project's Rights settings.
2. Click Show Detailed Permissions to reveal two additional permission types: Set DP History and Delete DP History.
3. You must have the Delete DP History right assigned to your account in order to delete historical data.

1. Open the project in Mervis SCADA (web interface).
2. Navigate to the Graph view for the datapoint containing the data you want to remove.
3. Click Show/Hide Series Points to display the individual data points along the series — this makes it much easier to click and select the exact point(s) you intend to delete.
4. Carefully select only the data you want to remove. Since this action can permanently affect the database, confirm your selection matches your intent before continuing.

Example use case: A sensor briefly malfunctions and records a single unrealistic spike in an otherwise smooth temperature trend. Using Show/Hide Series Points, you can isolate and select just that one erroneous point without affecting the surrounding valid data.

1. With your data selected, trigger the delete action. A Confirm Action dialog will appear.
2. This first dialog offers two options:
   • Yes — Deletes the selected data from the web GUI display only. The underlying data in the database is not affected.
   • No — Does not cancel the operation. Instead, a second Confirm Action dialog appears.
3. If a second dialog appears, it will ask you to confirm permanent deletion from the database. Confirming this step permanently and irreversibly removes the selected data from the underlying database.

Note: Because clicking “No” on the first dialog leads toward permanent deletion rather than cancelling, always read each confirmation dialog carefully before clicking anything.

• Graphs – General guide to visualizing and navigating historical data.
• Upload Historical Data – The reverse operation: importing historical data into a datapoint.