Synopsis

A function; calculates Calculates the average of the values in a specified column of the search query results.

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From the events in access log, returns the average of the values in column Bytes Sent.

Example 2:  

http in log.iis log | avg time-taken | group by sc-status 

From the events in log.iss log that contain http in their column values, returns the average of the values in column time-taken, grouped according to the value of the sc-status column.