What does the term "Delta" in data history refer to?

The term "Delta" in data history specifically refers to the point at which there is a change in tag value or quality. This means that each time the system detects a variation, whether in the actual measured value of a tag or the quality of that data (for instance, changes due to noise or equipment conditions), a new record is generated. This approach allows for efficient data storage and retrieval since it captures only significant changes rather than every single data point in a continuous flow.

This selective logging is critical in environments where data volumes can be substantial, helping to maintain database performance without compromising the integrity of the historical data. The emphasis is on changes that are relevant to users analyzing trends, making decisions, or troubleshooting issues. By capturing such deltas, the system effectively enables detailed tracking of how values evolve over time while avoiding redundancy.