AVG

Returns the average of numeric values.

Syntax

-- As an aggregate
AVG( expr )

-- As a window function
AVG ( expr ) OVER (
         [ PARTITION BY value_expression [, ...] ]
         [ ORDER BY value_expression [ ASC | DESC ] [ NULLS { FIRST | LAST } ] [, ...] ]
         [ frame_clause ]
      )

Arguments

Parameter	Description
expr	Numeric expression

Returns

Return type is dependant on the argument.

• For TINYINT, SMALLINT and INT, the return type is INT.

• For BIGINT, the return type is BIGINT.

• For REAL, the return type is REAL

• For DOUBLE, rhe return type is DOUBLE

Notes

• NULL values are ignored

• AVG relies on calculating the sum, which can very quickly overflow on large data sets. If the sum is over 2³¹ for example, up-cast to a larger type like BIGINT: AVG(expr :: BIGINT)

Examples

For these examples, assume a table named nba, with the following structure:

CREATE TABLE nba
(
   "Name" text(40),
   "Team" text(40),
   "Number" tinyint,
   "Position" text(2),
   "Age" tinyint,
   "Height" text(4),
   "Weight" real,
   "College" text(40),
   "Salary" float
 );

Here’s a peek at the table contents (Download nba.csv):

nba.csv

Name	Team	Number	Position	Age	Height	Weight	College	Salary
Avery Bradley	Boston Celtics	0.0	PG	25.0	6-2	180.0	Texas	7730337.0
Jae Crowder	Boston Celtics	99.0	SF	25.0	6-6	235.0	Marquette	6796117.0
John Holland	Boston Celtics	30.0	SG	27.0	6-5	205.0	Boston University
R.J. Hunter	Boston Celtics	28.0	SG	22.0	6-5	185.0	Georgia State	1148640.0
Jonas Jerebko	Boston Celtics	8.0	PF	29.0	6-10	231.0		5000000.0
Amir Johnson	Boston Celtics	90.0	PF	29.0	6-9	240.0		12000000.0
Jordan Mickey	Boston Celtics	55.0	PF	21.0	6-8	235.0	LSU	1170960.0
Kelly Olynyk	Boston Celtics	41.0	C	25.0	7-0	238.0	Gonzaga	2165160.0
Terry Rozier	Boston Celtics	12.0	PG	22.0	6-2	190.0	Louisville	1824360.0

Simple average

t=> SELECT AVG("Age") FROM nba;
avg
---
26

Note

The return type is the same as the input type. To get a fractional result, cast the argument:

t=> SELECT AVG("Age" :: REAL) FROM nba;
avg
-------
26.9387

Combine AVG with other aggregates

t=> SELECT "Age", AVG("Salary") as "Average salary", COUNT(*) as "Number of players" FROM nba GROUP BY 1;
Age | Average salary | Number of players
----+----------------+------------------
 19 |        1930440 |                 2
 20 |        2725790 |                19
 21 |        2067379 |                19
 22 |        2357963 |                26
 23 |        2034746 |                41
 24 |        3785300 |                47
 25 |        3930867 |                45
 26 |        6866566 |                36
 27 |        6676741 |                41
 28 |        5110188 |                31
 29 |        6224177 |                28
 30 |        7061858 |                31
 31 |        8511396 |                22
 32 |        7716958 |                13
 33 |        3930739 |                14
 34 |        7606030 |                10
 35 |        3461739 |                 9
 36 |        2238119 |                10
 37 |       12777778 |                 4
 38 |        1840041 |                 4
 39 |        2517872 |                 2
 40 |        4666916 |                 3