Question

I have a table tips that is defined as follows:

CREATE TABLE tips
(
  tip_id bigserial NOT NULL,
  tip text NOT NULL,
  author text NOT NULL,
  post_date bigint NOT NULL,
  likers character varying(16)[],
  dislikers character varying(16)[],
  likes integer NOT NULL,
  dislikes integer NOT NULL,
  abuse_history character varying(16)[]
);

I need to get the tips based on popularity, with the definition of popularity being:
likes – dislikes – (size(abuse_history)*5)

The query below gives me the same results regardless of the sort order (ASC/DESC).

select * from tips order by (likes - dislikes - (array_length(abuse_history,1) * 5)) ASC limit 2147483647 offset 0

EDIT

I inserted 3 records that have the following values:
1) 1 like, 0 dislikes, 0 abuse complaints
2) 0 likes, 1 dislike, 0 abuse complaints
3) 0 likes, 0 dislikes, 0 abuse…

Regardless of the sort order (ASC/DESC), I get the following order:
{3, 1, 2}

Could anyone please point me in the right direction?

Answer 1

Consider this:

SELECT array_length('{}'::character varying(16)[], 1);  -- null

Output is null for an empty array. Also, your abuse_history can be null itself. So you need something like this:

SELECT tip_id
     , likes
     , dislikes
     , (likes - dislikes - COALESCE(array_upper(abuse_history,1) * 5,0)) as pop
     , (likes - dislikes - array_upper(abuse_history,1) * 5) AS fail_pop
FROM   tips
ORDER  BY pop DESC;

fiddle

Sample output:

 tip_id | likes | dislikes | pop | fail_pop
--------+-------+----------+-----+----------
      1 |     1 |        0 |   1 |
      2 |     1 |        0 |   1 |
      4 |     0 |        0 |   0 |
      3 |     0 |        1 |  -1 |
      5 |     1 |        0 | -14 |      -14