Aggregate Functions

The following operators can be used in aggregate queries.

Any/All

Given an expression, return true if the expression is true for any or all events in the stream.

select any(@Level = 'Error') from stream

Given a property name, computes the number of events that have a non-null value for that property.

The special property name * can be used to count all events.

select count(*) from stream where has(@Exception)

Given a property name or expression, computes the set of distinct values for that expression.

select distinct(ExceptionType) from stream where Application like 'Admissions%'

distinct() and count() can be combined to count distinct values without returning them all.

select count(distinct(ExceptionType)) from stream

Given an expression, returns the value of that expression applied to the first or last events in the target range.

select first(Elapsed), last(Elapsed) from stream group by time(5m)

In a query that groups by time, the duration of each time slice.

select count(*) / (interval() / 1d) as per_day
from stream
group by time(30d)

Given a numeric expression or property name, computes the smallest or largest value for that expression.

select min(Elapsed / 1000) as ElapsedSeconds from stream group by time(1h)

Computes the arithmetic mean (average) of a numeric expression or property, i.e. sum(expr) / count(expr).

select mean(ItemCount) from stream group by ItemId

Events where the expression is null or not numeric are ignored and do not contribute to the final result.

Given an expression and a percentage p, calculates the value of the expression at or below which p percent of the results fall.

select percentile(ResponseTime, 95) from stream group by time(1h), MachineName

This is the nearest rank percentile.

Given an expression or property name, calculates the sum of that value.

select sum(ItemsOrdered) from stream group by ItemId

Non-numeric results are ignored.

Selects the first or last n values of an expression.

select top(ExceptionType, 10) from stream where Application <> 'Admissions'