Today I learned about postgres with clause

A with clause can be used to create a temporary table that can be used in the query. This is useful when you want to use the same subquery multiple times in the main query.

WITH total_activities AS (
  SELECT a.profile_id, count(a.id) AS activity_count 
  FROM activities a
  GROUP BY profile_id
)
SELECT * FROM total_activities 
UNION ALL
SELECT 0, sum(activity_count) FROM total_activities
ORDER BY profile_id

In the above query, total_activities is a temporary table that is created using the with clause. This temporary table is then used in the main query to get the total count of activities for each profile and also the sum of all activities.