How to group by week in postgresql

Question

I\'ve a database table commits with the following columns:

id | author_name | author_email | author_date (timestamp) | total_lines

Answer 1

It has been very long since this question was asked.
Anyways, if at all anyone comes through this.

If you want the count of all the intermediate weeks as well where there are no commits/records, you can get it by providing a start_date and end_date to generate_series() function

SELECT t1.year_week week, 
       t2.commit_count 
FROM   (SELECT week, 
               To_char(week, 'IYYY-IW') year_week 
        FROM   generate_series('2020-02-01 06:06:51.25+00'::DATE, 
               '2020-04-05 12:12:33.25+00':: 
               DATE, '1 week'::interval) AS week) t1 
       LEFT OUTER JOIN (SELECT To_char(author_date, 'IYYY-IW') year_week, 
                               COUNT(author_email)             commit_count 
                        FROM   commits 
                        GROUP  BY year_week) t2 
                    ON t1.year_week = t2.year_week; 

The output will be:

     week | commit_count  
----------+-------------
2020-05   | 2
2020-06   | NULL  
2020-07   | 1