discourse/app/models/hot_topic.rb
2013-03-29 13:33:31 -04:00

61 lines
2.5 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
# Include high percentile recent topics
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.archetype <> :private_message
AND created_at >= (CURRENT_TIMESTAMP - INTERVAL ':days_ago' DAY)
AND t.percent_rank < :hot_percentile
LIMIT :limit",
hot_percentile: hot_percentile,
limit: ((1.0 - older_percentage) * max_hot_topics).round,
private_message: Archetype::private_message,
days_ago: new_days)
# 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()
FROM topics AS t
WHERE t.deleted_at IS NULL
AND t.visible
AND (NOT t.closed)
AND (NOT t.archived)
AND t.archetype <> :private_message
AND created_at < (CURRENT_TIMESTAMP - INTERVAL ':days_ago' DAY)
AND t.percent_rank < :hot_percentile
LIMIT :limit",
hot_percentile: hot_percentile,
limit: (older_percentage * max_hot_topics).round,
private_message: Archetype::private_message,
days_ago: new_days)
end
end
end