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 site settings as multipliers:
top topics formula log views multiplier
top topics formula first post likes multiplier
-
top topics formula least likes per post multiplier
Calculation steps
Calculate a top score for each topic by adding together the following:
- The number of views 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 multiplier
value
- 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 post
-10
- The number of posts 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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