This is a reference guide explaining how topics filtered by “Top” are determined to be “Top Topics” in Discourse.
Required user level: All users
Discourse sites have a feature that allows users to sort topics by “Top”. This guide explains how these “Top” topics are calculated and displayed.
Summary
- All “Top” topics are assigned a “Top Score”
- The score is based on likes, replies, and views within a selected time period
- Topics with the highest “Top Score” appear at the top of the list
Top Score calculation
The “Top Score” for a topic is calculated using the following factors:
- Number of views
- Likes on the first post
- Likes on subsequent posts
- Number of replies
The calculation uses three hidden site settings as multipliers (these are not visible in the admin settings UI, but can be changed via the Rails console or API):
-
top topics formula log views multiplier(default:2) -
top topics formula first post likes multiplier(default:0.5) -
top topics formula least likes per post multiplier(default:3)
Calculation steps
Calculate a top score for each topic by adding together the following:
- The logarithm of the number of views (minimum 1) for each topic in the selected period, multiplied by the
log views multiplier - The number of likes on the original post of the topic multiplied by the
first post likes multiplier - The lesser of:
- The average likes per post (total likes on the topic divided by the number of posts)
- The
least likes per post multipliervalue
- If the period has less than 10 posts, perform the following calculation:
Otherwise,0 - ((10 - number of posts in the topic) / 20) * number of likes on the original post10 - The logarithm of the number of posts (minimum 1) on the topic
Viewing Top Topics
You can see an example of Top Topics on a Discourse site in the image below:
Additional resources
For more technical details, you can refer to:
- The Ruby source code for the top calculation: discourse/app/models/top_topic.rb at main · discourse/discourse · GitHub
- This Data Explorer query to see the exact “Top Score” for each topic:
-- [params]
-- date :start_date = 26 apr 2020
-- date :end_date = 2 may 2020
-- double :log_views_multiplier = 2.0
-- double :first_post_likes_multiplier = 0.5
-- double :least_likes_per_post_multiplier = 3.0
WITH likes AS (
SELECT topic_id, SUM(like_count) AS count
FROM posts
WHERE created_at::date >= :start_date::date
AND created_at::date < :end_date::date
AND deleted_at IS NULL
AND NOT hidden
AND post_type = 1
GROUP BY topic_id
),
op_likes AS (
SELECT topic_id, like_count AS count
FROM posts
WHERE created_at::date >= :start_date::date
AND created_at::date < :end_date::date
AND post_number = 1
AND deleted_at IS NULL
AND NOT hidden
AND post_type = 1
),
posts AS (
SELECT topic_id, GREATEST(COUNT(*), 1) AS count
FROM posts
WHERE created_at::date >= :start_date::date
AND created_at::date < :end_date::date
AND deleted_at IS NULL
AND NOT hidden
AND post_type = 1
AND user_id <> 0
GROUP BY topic_id
),
views AS (
SELECT topic_id, COUNT(*) AS count
FROM topic_views
WHERE viewed_at::date >= :start_date::date
AND viewed_at::date < :end_date::date
GROUP BY topic_id
),
category_definition_topic_ids AS (
SELECT COALESCE(topic_id, 0) AS id FROM categories
),
top_topics AS(
SELECT
topics.id AS topic_id,
topics.title,
topics.user_id,
posts.count AS date_range_posts,
views.count AS date_range_views,
topics.views AS all_time_views,
topics.bumped_at,
(CASE
WHEN topics.created_at::date < :start_date::date
AND topics.created_at::date >= :end_date::date
THEN 0
ELSE log(GREATEST(views.count, 1)) * :log_views_multiplier +
op_likes.count * :first_post_likes_multiplier +
CASE WHEN likes.count > 0 AND posts.count > 0
THEN
LEAST(likes.count / posts.count, :least_likes_per_post_multiplier)
ELSE 0
END +
CASE WHEN topics.posts_count < 10 THEN
0 - ((10 - topics.posts_count) / 20) * op_likes.count
ELSE
10
END +
log(GREATEST(posts.count, 1))
END) AS score
FROM posts
INNER JOIN views ON posts.topic_id = views.topic_id
INNER JOIN likes ON posts.topic_id = likes.topic_id
INNER JOIN op_likes ON posts.topic_id = op_likes.topic_id
LEFT JOIN topics ON topics.id = posts.topic_id AND topics.deleted_at IS NULL
WHERE topics.deleted_at IS NULL
AND topics.visible
AND topics.archetype <> 'private_message'
AND NOT topics.archived
AND topics.id NOT IN (SELECT id FROM category_definition_topic_ids)
ORDER BY
score DESC,
topics.bumped_at DESC
)
SELECT * FROM top_topics WHERE score > 0
Last edited by @hugh 2024-07-02T04:15:57Z
Last checked by @hugh 2024-07-02T04:16:06Z
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