CQL native aggregates 

Works on a set of rows matching the SELECT statement to return a single value.

Aggregate functions work on a set of rows matching a SELECT statement to return a single value. Null values in the data set are ignored. When other columns, columns with user-defined types, or functions, are also specified in the selector clause of a SELECT statement with an aggregate function, the values in the first row matching the query are returned.
CAUTION:
Aggregating data across partitions may cause performance issues. DataStax recommends using aggregates on one partition, to get a list of partition keys use SELECT DISTINCT partition_key to get a list of unique keys (for compound keys use a comma separated list of column names).
Tip: Define custom aggregates using CREATE AGGREGATE.

Synopsis 

aggregate_name(column_name)
Where the system aggregate names are listed below:
AVG 
AVG(column_name): Provides the average value of the target column using the data type of target column. Null values are ignored.

Only works on numeric columns, that is tinyint, smallint, int, bigint, decimal, float, and double.

COUNT 
COUNT(column_name): Provides the number of rows in the result set that do not have null values. For a complete row count use partition key column, since partition keys cannot contain nulls.

Works on all CQL data types columns.

MIN 
MIN(column_name): Provides the smallest value. Null values are ignored.

Only works numeric columns, that is tinyint, smallint, int, bigint, decimal, float, and double.

MAX 
MAX(column_name): Provides the largest value. Null values are ignored.

Only works numeric columns, that is tinyint, smallint, int, bigint, decimal, float, and double.

SUM 
SUM(column_name): Provides the total of the target column; nulls are ignored.

Only works on numeric columns, that is tinyint, smallint, int, bigint, decimal, float, and double.

Examples 

The following examples show how to use aggregates using the cyclist examples.

Find Average (AVG)

Get average time in seconds for the team:
SELECT AVG(cyclist_time_sec) AS Average FROM cycling.team_average
WHERE team_name = 'UnitedHealthCare Pro Cycling Womens Team';
Results:
average
---------
  11474

(1 rows)

Find Count (COUNT)

Find the number rows for the United Health Care Pro Cycling Women's Team:
SELECT count(cyclist_name) AS Row_Count FROM cycling.team_average
WHERE team_name = 'UnitedHealthCare Pro Cycling Womens Team';
Results:
row_count
-----------
        3

(1 rows)

Find lowest value (MIN)

Find the slowest time recorded for the United Health Care Pro Cycling Women's Team:
SELECT MIN(cyclist_time_sec) AS Fastest FROM cycling.team_average
WHERE team_name = 'UnitedHealthCare Pro Cycling Womens Team';
Results:
fastest
---------
  11449

(1 rows)

Find highest value (MAX)

Find the fastest time recorded for the United Health Care Pro Cycling Women's Team:
SELECT MAX(cyclist_time_sec) AS Slowest FROM cycling.team_average
WHERE team_name = 'UnitedHealthCare Pro Cycling Womens Team';
Results:
slowest
---------
  11490

(1 rows)

Find total (SUM)

Find the total of all times recorded for the United Health Care Pro Cycling Women's Team:
SELECT SUM(cyclist_time_sec) AS Total_Time FROM cycling.team_average
WHERE team_name = 'UnitedHealthCare Pro Cycling Womens Team';
Results:
total_time
------------
     34424

(1 rows)