discourse/app/models/hot_topic.rb

88 lines
3.9 KiB
Ruby

class HotTopic < ActiveRecord::Base
belongs_to :topic
belongs_to :category
# Here's the current idea behind the implementaiton of hot: random can produce good results!
# Hot is currently made up of a random selection of high percentile topics. It includes mostly
# new topics, but also some old ones for variety.
def self.refresh!
transaction do
exec_sql "DELETE FROM hot_topics"
# TODO, move these to site settings once we're sure this is how we want to figure out hot
max_hot_topics = 200 # how many hot topics we want
hot_percentile = 0.2 # What percentile of topics we consider good
older_percentage = 0.2 # how many old topics we want as a percentage
new_days = 21 # how many days old we consider old
no_old_in_first_x_rows = 8 # don't show old results in the first x rows
# Include all sticky uncategorized on Hot
exec_sql("INSERT INTO hot_topics (topic_id, score)
SELECT t.id, RANDOM()
FROM topics AS t
WHERE t.deleted_at IS NULL
AND t.visible
AND (NOT t.archived)
AND t.pinned_at IS NOT NULL
AND t.category_id IS NULL")
# Include high percentile recent topics
inserted_count = exec_sql("INSERT INTO hot_topics (topic_id, category_id, score)
SELECT t.id,
t.category_id,
((1.0 - (EXTRACT(EPOCH FROM CURRENT_TIMESTAMP-t.created_at)/86400) / :days_ago) * 0.95) +
(RANDOM() * 0.05)
FROM topics AS t
WHERE t.deleted_at IS NULL
AND t.visible
AND (NOT t.closed)
AND (NOT t.archived)
AND t.pinned_at IS NULL
AND t.archetype <> :private_message
AND created_at >= (CURRENT_TIMESTAMP - INTERVAL ':days_ago' DAY)
AND t.percent_rank < :hot_percentile
AND NOT EXISTS(SELECT * FROM hot_topics AS ht2 WHERE ht2.topic_id = t.id)
LIMIT :limit",
hot_percentile: hot_percentile,
limit: ((1.0 - older_percentage) * max_hot_topics).round,
private_message: Archetype::private_message,
days_ago: new_days)
max_old_score = 1.0
# Finding the highest score in the first x rows
if HotTopic.count > no_old_in_first_x_rows
max_old_score = HotTopic.order('score desc').limit(no_old_in_first_x_rows).last.score
end
# Add a sprinkling of random older topics
exec_sql("INSERT INTO hot_topics (topic_id, category_id, score)
SELECT t.id,
t.category_id,
RANDOM() * :max_old_score
FROM topics AS t
WHERE t.deleted_at IS NULL
AND t.visible
AND (NOT t.closed)
AND (NOT t.archived)
AND t.pinned_at IS NULL
AND t.archetype <> :private_message
AND created_at < (CURRENT_TIMESTAMP - INTERVAL ':days_ago' DAY)
AND t.percent_rank < :hot_percentile
AND NOT EXISTS(SELECT * FROM hot_topics AS ht2 WHERE ht2.topic_id = t.id)
LIMIT :limit",
hot_percentile: hot_percentile,
limit: (older_percentage * max_hot_topics).round,
private_message: Archetype::private_message,
days_ago: new_days,
max_old_score: max_old_score)
end
end
end