Synchronised and Scattered Historical Sources
There are two main ways of recording your history.
In most cases, marking your data source as sychronised will result in significantly better read performance and less server load.
Synchronised
Synchronised recording is when you store the information about all of your values at the same time. This means that when you look at your recorded data, there's a complete snapshot with the same date-stamp.
| Date | Name | Value |
| 2012-02-03 09:00:00 | Alpha.Pressure | 1922 |
| 2012-02-03 09:00:00 | Beta.Pressure | 2883 |
| 2012-02-03 09:00:00 | Gamma.Pressure | 5558 |
| 2012-02-03 08:00:00 | Alpha.Pressure | 1922 |
| 2012-02-03 08:00:00 | Beta.Pressure | 3922 |
| 2012-02-03 08:00:00 | Gamma.Pressure | 3992 |
Above, you'll see that there are a complete set of values recorded at 9:00, even though there was no change in the 'Alpha.Pressure' value. This is a synchronised recording.
Scattered
Scattered recording either only records the changes in your data, or records all of your points at different times and rates.
| Date | Name | Value |
| 2012-02-03 09:00:00 | Beta.Pressure | 2883 |
| 2012-02-03 08:30:00 | Gamma.Pressure | 5558 |
| 2012-02-03 08:15:00 | Gamma.Pressure | 2247 |
| 2012-02-03 08:00:00 | Alpha.Pressure | 1922 |
| 2012-02-03 08:00:00 | Beta.Pressure | 3922 |
| 2012-02-03 08:00:00 | Gamma.Pressure | 3992 |
Above, you'll see that there is only a single record for Alpha pressure, while there are many more for Gamma.
Note that while scattered recording is significantly more efficient in terms of server write load and drive usage, it's much more expensive to read. This is why the ARDI Recorder addon performs synchronised recording.