AVG window function - Amazon Redshift
SyntaxArgumentsData typesExamples
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AVG window function

The AVG window function returns the average (arithmetic mean) of the input expression values. The AVG function works with numeric values and ignores NULL values.

Syntax

AVG ( [ALL ] expression ) OVER
(
[ PARTITION BY expr_list ]
[ ORDER BY order_list 
                        frame_clause ]
)

Arguments

expression

The target column or expression that the function operates on.

ALL

With the argument ALL, the function retains all duplicate values from the expression for counting. ALL is the default. DISTINCT is not supported.

OVER

Specifies the window clauses for the aggregation functions. The OVER clause distinguishes window aggregation functions from normal set aggregation functions.

PARTITION BY expr_list

Defines the window for the AVG function in terms of one or more expressions.

ORDER BY order_list

Sorts the rows within each partition. If no PARTITION BY is specified, ORDER BY uses the entire table.

frame_clause

If an ORDER BY clause is used for an aggregate function, an explicit frame clause is required. The frame clause refines the set of rows in a function's window, including or excluding sets of rows within the ordered result. The frame clause consists of the ROWS keyword and associated specifiers. See Window function syntax summary.

Data types

The argument types supported by the AVG function are SMALLINT, INTEGER, BIGINT, NUMERIC, DECIMAL, REAL, and DOUBLE PRECISION.

The return types supported by the AVG function are:

  • BIGINT for SMALLINT or INTEGER arguments

  • NUMERIC for BIGINT arguments

  • DOUBLE PRECISION for floating point arguments

Examples

The following example computes a rolling average of quantities sold by date; order the results by date ID and sales ID: 

select salesid, dateid, sellerid, qty,
avg(qty) over
(order by dateid, salesid rows unbounded preceding) as avg
from winsales
order by 2,1;

salesid |   dateid   | sellerid | qty | avg
---------+------------+----------+-----+-----
30001 | 2003-08-02 |        3 |  10 |  10
10001 | 2003-12-24 |        1 |  10 |  10
10005 | 2003-12-24 |        1 |  30 |  16
40001 | 2004-01-09 |        4 |  40 |  22
10006 | 2004-01-18 |        1 |  10 |  20
20001 | 2004-02-12 |        2 |  20 |  20
40005 | 2004-02-12 |        4 |  10 |  18
20002 | 2004-02-16 |        2 |  20 |  18
30003 | 2004-04-18 |        3 |  15 |  18
30004 | 2004-04-18 |        3 |  20 |  18
30007 | 2004-09-07 |        3 |  30 |  19
(11 rows)

For a description of the WINSALES table, see Sample table for window function examples.