func.first_value
FIRST_VALUE is an analytic function. It returns the first value in an ordered set of values
Syntax
func.first_value(field).over(partition_by=field, order_by=field)
Examples
This is an example of using the first_value() capability to calculate the running time of the time series data where each event is on a distinct row.
This assumes you have a table of time series data that looks like this:
| location | employee | timestamp |
|---|---|---|
| Building A | John Doe | 2022-01-05 15:34:31 |
| Building A | John Doe | 2022-01-05 15:44:31 |
| Building A | John Doe | 2022-01-05 15:46:41 |
table.timestamp - func.first_value(table.timestamp, 1).over(partition_by=[table.location, table.employee], order_by=table.timestamp)
Adding the expression above to an Interval column called run_time would result in an output table like this:
| location | employee | timestamp | run_time |
|---|---|---|---|
| Building A | John Doe | 2022-01-05 15:34:31 | 00:00:00 |
| Building A | John Doe | 2022-01-05 15:44:31 | 00:10:00 |
| Building A | John Doe | 2022-01-05 15:46:41 | 00:12:10 |
Last modified April 06, 2022 at 10:08 AM EST: Initial Documentation Commit (371ae8f)