GROUP BY clause - Amazon Redshift

GROUP BY clause

The GROUP BY clause identifies the grouping columns for the query. Grouping columns must be declared when the query computes aggregates with standard functions such as SUM, AVG, and COUNT. For more information, see Aggregate functions.

Syntax

GROUP BY group_by_clause [, ...] group_by_clause := { expr | GROUPING SETS ( () | group_by_clause [, ...] ) | ROLLUP ( expr [, ...] ) | CUBE ( expr [, ...] ) }

Parameters

expr

The list of columns or expressions must match the list of non-aggregate expressions in the select list of the query. For example, consider the following simple query.

select listid, eventid, sum(pricepaid) as revenue, count(qtysold) as numtix from sales group by listid, eventid order by 3, 4, 2, 1 limit 5; listid | eventid | revenue | numtix -------+---------+---------+-------- 89397 | 47 | 20.00 | 1 106590 | 76 | 20.00 | 1 124683 | 393 | 20.00 | 1 103037 | 403 | 20.00 | 1 147685 | 429 | 20.00 | 1 (5 rows)

In this query, the select list consists of two aggregate expressions. The first uses the SUM function and the second uses the COUNT function. The remaining two columns, LISTID and EVENTID, must be declared as grouping columns.

Expressions in the GROUP BY clause can also reference the select list by using ordinal numbers. For example, the previous example could be abbreviated as follows.

select listid, eventid, sum(pricepaid) as revenue, count(qtysold) as numtix from sales group by 1,2 order by 3, 4, 2, 1 limit 5; listid | eventid | revenue | numtix -------+---------+---------+-------- 89397 | 47 | 20.00 | 1 106590 | 76 | 20.00 | 1 124683 | 393 | 20.00 | 1 103037 | 403 | 20.00 | 1 147685 | 429 | 20.00 | 1 (5 rows)
GROUPING SETS/ROLLUP/CUBE

You can use the aggregation extensions GROUPING SETS, ROLLUP, and CUBE to perform the work of multiple GROUP BY operations in a single statement. You can only use aggregation extensions on preview clusters or preview serverless workgroups. For more information on aggregation extensions and related functions, see Aggregation extensions (preview) .