History group functions
About historical values
Historical values means that previously saved values are not overwritten when saving new values. The figure below shows a time series having values with various write times. The Calculator returns the values indicated by red when you ask for the most recently written historical values written before tc.
In the picture above, the values are written in a scattered way. There are other series where contents are updated more regularly, typical forecast series where a fixed number of points are written. The start time for each forecast will normally follow current storage time in some way. For example a precipitation forecast received/stored two times a day containing hourly values for six days ahead.
There is a dedicated set of history functions to extract values from a versioned time series associated with this storage pattern.
Hourly example data
In the function descriptions there are some examples based on a sequence of write operations. These values are presented in a Nimbus client view shown below. The header text for each version gives information on the validity interval for which the time series had the values shown in each column:
The values within the given time period scope are created from 5 separate write operations taking place at 6th November 2025:
- At 14:20:19 (UTC+1) value 1.0 is stored on 48 hours from beginning of day (UTC+1)
- At 14:20:58 (UTC+1) value 2.0 is stored on 48 hours from 04:00 (UTC+1)
- At 14:21:28 (UTC+1) value 3.0 is stored on 48 hours from 08:00 (UTC+1)
- At 14:22:11 (UTC+1) value 4.0 is stored on 48 hours from 12:00 (UTC+1)
- At 14:22:40 (UTC+1) value 4.1 is stored for 8 hours from 17:00 (UTC+1)
The value write operations are also shown below:
