What Happens if you Backfill Historic Data into a Point?
When you backfill historic data values into a point, those values are marked as 'out of sequence' by the Sparkplug Publisher driver. A value is marked as 'out of sequence' when it is older than the latest value that the Sparkplug Publisher has already published for that particular point.
You can only backfill the data values that have been recorded since that point was configured in the Sparkplug Publisher driver.
Out of sequence values are assigned an 'is_historical = true' flag. This flag allows the Sparkplug client to identify out of sequence values and to process them differently to other historic values.
A point, 'PointA', published its latest value on 2025-05-30 11:25:47 (30th May), while another point, 'PointB' published its latest value on 2025-05-28 12:06:32 (28th May).
If you then import a value with a timestamp of 2025-05-29 10:05:32 (29th May) into PointA, that value will be assigned the 'is_historical = true' flag. This is because the timestamp of this value is older than that of the last published value by the point, making it out of sequence.
However, if you import a value with that timestamp into PointB, it will be assigned the 'is_historical = false' flag. This value is not considered out of sequence for PointB because its timestamp is later than that of the last value published by that particular point.
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