sql window function

window functions

• https://www.postgresql.org/docs/current/functions-window.html

SELECT {columns},
{window_func} OVER (PARTITION BY {partition_key} ORDER BY {order_key})
FROM table1;

Window functions create aggregates without flattening the data into a single row. However, they replicate it for all the rows to which the grouping functions refer.

select category, count(*) over (partition by category) from posts order by category;