delta Metrics Operator

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.

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.

Syntax

delta [increasing | decreasing | counter]

When deciding which mode you should use, here are some guidelines:

• You need to get the difference of a counter - use delta counter.
• You need to get the difference of a non-counter metric - use delta.

You can also use the increasing or decreasing option to make delta consider only pairs of consecutive points where the second point is greater (increasing option) or less (decreasing option) than the first point. However, these options are mostly kept for backward compatibility and so their usage is not recommended.

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

Positive difference in a metric over time

This query returns a time series that reflects the difference in the elasticsearch_jvm_mem_heap_used_in_bytes metric between a charted value and the one preceding it, only considering pairs of consecutive points where the second point is greater than the first point.

metric=elasticsearch_jvm_mem_heap_used_in_bytes | delta increasing

Difference in a counter over time

This query returns a time series that reflects the difference in the apiserver_request_total counter between a charted value and the one preceding it, accounting for counter resets.

metric=apiserver_request_total | delta counter