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Sumo Logic

smooth

The smooth operator calculates the rolling (or moving) average of a field, measuring the average of a value to "smooth" random variation. Smooth operator reveals trends in the data set you include in a query.

Within a query that contains a smooth operator you'll choose a window (described as window_length in syntax below); the average of the values within the window creates a data point.

If you specify a window length of 5, but only 4 data points are available, the smooth operator takes the average of whatever is available.

Adding a group by function to a smooth operator query produces a running average within each group (with data from each group calculated separately).

Syntax:

  • ... smooth field [, window_length]

Rules:

  • An alias for smooth is optional. When an alias is not provided, _smooth is the default alias.
  • Specified fields must contain numeric values.
  • To add a query that includes a smooth operator to a Dashboard, you must add a group by function before the smooth operator.
  • The default window length is 10.
  • The maximum window length is 1000.

Examples

Use smooth to see the difference of fields between time points, grouped by source host.

Running a query such as:

_sourcecategory=katta 
| timeslice by 1m 
| count by _timeslice,_sourcehost 
| sort + _timeslice 
| smooth _count,1 by _sourcehost

produces results like:

smooth1.png

Smooth the difference of a quantity between time points.

Using smooth with timeslice, you can run a query similar to:

* | parse "bytes transmitted: '*'" as bytes 
| timeslice 1m 
| sum(bytes) as bytes by _timeslice 
| sort _timeslice 
| smooth bytes, 5

that produces results like:

smooth.png

Use backshift with smooth and rollingstd to view the averages of incoming bytes.

Running a query like:

...| timeslice by 1m
| avg(oneMinuteRate) as avgRateByHost by _sourcehost,_timeslice
| sum(avgratebyhost) as totalIncomingRate by _timeslice
| sort + _timeslice
| backshift totalIncomingRate, 1 as lagRate
| smooth lagRate,10 as movingAvg
| rollingstd lagRate,10 as rollingStd
| movingAvg + (3 * rollingStd) as upper
| movingAvg - (3 * rollingStd) as lower

produces results similar to:

OneMinuteRate.png

Specify a window length of 5, but only 4 data points are available.

Before 5 values are available, the smooth operator takes an average of whatever is available. For example:

_sourcecategory=katta 
| timeslice by 1m 
| count by _timeslice,_sourcehost 
| where _sourcehost="nite-katta-cold-4" 
| sort + _timeslice 
| smooth _count,5

produces results like:

Coldsmooth.png