My customer wrongly requested that I delete a tag and now wants it restored.
Using a gateway backup, I exported and then imported the required tag back into Ignition. I have updated the sqlth_te table so that this tag’s retired value is returned to NULL.
I can assign the tag in the ad hoc chart, but I cannot see any of the historical data that was captured. What do I need to do to resolve this?
Check sqlth_te for duplicates. The most likely explanation I can provide is that a new entry was added, and is the one used.
When you edited the table, it made no difference as the cache was still showing a retired tag entry at this path and a new one was created.
When you manually edit the historian tables, make sure to restart the history provider to make it rebuild its cache.
Hi Pascal, thanks for the feedback. Yes, you were correct, there were two entries in sqlth_te with the most recent entry generated from the recent import.
I have deleted the latest entry and restarted the historian, but still, no historical data is available. Do you have any further suggestions, please?
There's a chance tags have a hidden, internal id, and that it doesn't match.
But that's way out of my knowledge, you'll have better answers from someone else (most likely Paul or Phil).
I kinda wish you had not deleted the latest entry yet. You should have checked some of its meta data first, following the scid -> drvid trail.
For now I guess you can check what happens when your tag gets new data: Is that data sent to the current entry in sqlth_te ? Or is a new one created ?