# delta

The delta operator computes the backward difference at each data point in the time series to determine how much the metric has changed from its last value in the series.

Computes the backward difference at each data point in the time series to determine how much the metric has changed from its last value in the series.

The `delta`

operator updates the `metric`

dimension, if present, to `delta($metric)`

. If the original time series does not have a `metric`

dimension, it creates `metric=delta`

dimension. Other dimensions remain unaffected.

### delta syntax

`metric query | delta`

### delta examples

#### Difference in a metric value from previous point

This query returns a time series that reflects the difference in the `Net_InBytes`

metric for the eth0 interface between a charted value and the one preceding it.

`metric=Net_InBytes Interface=eth0 | delta`