Query first and last values

Use first() or last() to return the first or last record in an input table.

data
    |> first()

// OR

data
    |> last()

first

first() returns the first non-null record in an input table.

|> first()

last

last() returns the last non-null record in an input table.

|> last()

Use first() or last() with aggregateWindow()

Use first() and last() with aggregateWindow() to select the first or last records in time-based groups. aggregateWindow() segments data into windows of time, aggregates data in each window into a single point using aggregate or selector functions, and then removes the time-based segmentation.

|> aggregateWindow(every: 1h, fn: first)

|> aggregateWindow(every: 1h, fn: last)