Latent Tag History

Ignition
, ,
1

I have noticed odd results when querying Ignition’s “sqlt_data_” tables. I executed a query that selected all records with a “t_stamp” from the previous minute. The number of records remained constant until a few days later when 180 additional records were discovered for the same time period. This caused a 10% increase in records. Is this delay expected or normal behaviour in some cases?

The backfilled records were an assortment of dnp3 devices (majority of connected devices are). No uncharacteristic system events were observed during this time.

Perspective 8.1.41

2

It is normal for any historized tag that uses "analog" deadband style. Which includes "auto" deadband style if the tag datatype is floating point.

Generally, you should not be querying Ignition's data partition tables directly, as you will miss recent information that is being held in memory, awaiting a decision point.