Let’s see how to use the Postgres ARRAY_AGG as a window function in this article. Bobcares, as a part of our PostgreSQL Support offers solutions to every query that comes our way.

Use of the Postgres “ARRAY_AGG” as a Window Function

ARRAY_AGG() in PostgreSQL is an aggregate function that takes a set of values and returns an array with a value for each set value allocated to an element of the array.

The basic syntax is as follows:

The ARRAY_AGG() accepts expressions that return valid values of any type for array elements. It’s optional to include the ORDER BY clause. The elements in the result array are in order according to the processing order of the rows during the aggregate.

Similar to other aggregate operations like AVG(), COUNT(), MAX(), MIN(), and SUM(), we can use the GROUP BY clause often in conjunction with ARRAY_AGG().

Example

Consider a table company containing the columns owner, month, and profit_amount. While keeping the context of the window partition (in this case, the owner), we can make an array of monthly profit for each owner using the array_agg:

In this example, each owner partition’s profit_amount values are organized into an array using the array_agg function, and the data are sorted by month. As a result, each owner experiences a range of monthly profit totals. Thus, Window functions in PostgreSQL can carry out more challenging analytical tasks, as shown by the use of array_agg as a window function.

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Conclusion

This article explains the use of the ARRAY_AGG function in Postgres as a Window function.