* Favoring single SQL and computation over enum
Prior to this commit, we ran a SQL statement to generate a list of
articles then applied some minor randomization.
With this commit, I'm removing the randomization in favor of expected
values, and collapsing the result set into a single inline SQL and some
post query simple arithmatic.
Let's check my math. For each article we sum:
* `article.score`
* `article.comments_count` * 14
* a random number between 0 and 5 (`rand(6)`) with expected value of 2.5
* the tag's (taggings_count + 1) / 2
The new SQL query sums the `article.score` and the
`article.comments_count` * 14. I then reduce the remainder of the
equation. From "for each article sum `(rand(5) + (taggings_count + 1) /
2)`" we have the following:
`article_count * (2.5 + (taggings_count + 1) / 2)`
Which is equivalent to:
`article_count * ((taggings_count + 1 + (2.5 * 2)) / 2)`
Which is equivalent to:
`article_count * ((taggings_count + 6) / 2)`
This change reduces computation time by favoring expected values.
* Fixing broken behavior and adding comments
6d37f4303c