Documentation

Query first and last values

This page documents an earlier version of InfluxDB. InfluxDB v1.8 is the latest stable version. View this page in the v1.8 documentation.

See the equivalent InfluxDB v2.0 documentation: Query first and last values.

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

data
  |> first()

// OR

data
  |> last()

By default, InfluxDB returns results sorted by time, however you can use the sort() function to change how results are sorted. first() and last() respect the sort order of input data and return records based on the order they are received in.

first

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

Given the following input:

_time_value
2020-01-01T00:01:00Z1.0
2020-01-01T00:02:00Z1.0
2020-01-01T00:03:00Z2.0
2020-01-01T00:04:00Z3.0

The following function returns:

|> first()
_time_value
2020-01-01T00:01:00Z1.0

last

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

Given the following input:

_time_value
2020-01-01T00:01:00Z1.0
2020-01-01T00:02:00Z1.0
2020-01-01T00:03:00Z2.0
2020-01-01T00:04:00Z3.0

The following function returns:

|> last()
_time_value
2020-01-01T00:04:00Z3.0

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.

Given the following input:

_time_value
2020-01-01T00:00:00Z10
2020-01-01T00:00:15Z12
2020-01-01T00:00:45Z9
2020-01-01T00:01:05Z9
2020-01-01T00:01:10Z15
2020-01-01T00:02:30Z11

The following function returns:

|> aggregateWindow(
  every: 1h,
  fn: first
)
_time_value
2020-01-01T00:00:59Z10
2020-01-01T00:01:59Z9
2020-01-01T00:02:59Z11
|> aggregateWindow(
  every: 1h,
  fn: last
)
_time_value
2020-01-01T00:00:59Z9
2020-01-01T00:01:59Z15
2020-01-01T00:02:59Z11


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