title: Is it possible to find out the number of items in a row by using window functions in PostgreSQL?
body: <p>how to find the number of sellers who have payments, the time between which in a row is less than 1 minute and which are executed at least 3 times in a row? (answer is 2 sellers)
  and how to calculate the number of such payments? (answer is 10 payments)
  it seems like such a problem can be solved using window functions, but I have never encountered this kind of problem</p>
  <p><a href="https://i.stack.imgur.com/iSjvp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/iSjvp.png" alt="enter image description here" /></a></p>
  <pre><code>CREATE TABLE T (seller_id int, payment_id varchar(3), payment_time timestamp, second_diff int);
      
  INSERT INTO T (seller_id, payment_id, payment_time, second_diff)
  VALUES
      (1, 'pl',  '2015-01-08 09:23:04', 151),
      (1, 'p2',  '2015-01-08 09:25:35', 50),
      (1, 'p3',  '2015-01-08 09:26:25', 48),
      (1, 'p4',  '2015-01-08 09:27:23', 36),
      (1, 'p5',  '2015-01-08 09:27:59', 41),
      (1, 'p6',  '2015-01-08 09:28:40', 70),
      (1, 'p7',  '2015-01-08 09:29:50', 50),
      (1, 'p8',  '2015-01-08 09:30:40', 45),
      (1, 'p9',  '2015-01-08 09:31:25', 35),
      (1, 'p10', '2015-01-08 09:32:00', null),
      (2, 'pll', '2015-01-08 09:25:35', 25),
      (2, 'p12', '2015-01-08 09:26:00', 55),
      (2, 'p13', '2015-01-08 09:26:55', 30),
      (2, 'p14', '2015-01-08 09:27:25', 95),
      (2, 'p15', '2015-01-08 09:29:00', null),
      (3, 'p16', '2015-01-08 10:41:00', 65),
      (3, 'p17', '2015-01-08 10:42:05', 75),
      (3, 'p18', '2015-01-08 10:43:20', 90),
      (3, 'p19', '2015-01-08 10:43:20', 39),
      (3, 'p20', '2015-01-08 10:43:59', 50),
      (3, 'p21', '2015-01-08 10:44:49', null);
  </code></pre>