Number of occurrences within a specified window. This operation is frequently used in
alerting expressions to reduce noise. For example:
# Check to see if average cpu usage is > 80%
name,cpuUser,:eq,:avg,80,:gt,
# Only alert if that is true for more than 3 of the last 5
# datapoints
5,:rolling-count,3,:gt
A value is counted if it is non-zero. Missing values, NaN, will be treated as zeroes.
For example:
Input
3,:rolling-count
0
0
1
1
-1
2
NaN
2
0
1
1
1
1
2
1
3
1
3
0
2
The window size, n, is the number of datapoints to consider including the current
value. Note that it is based on datapoints not a specific amount of time. As a result the
number of occurrences will be reduced when transitioning to a larger time frame that
causes consolidation.
