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, random_bias, random_multiplier, days_ago_bias, days_ago_multiplier, score, hot_topic_type) SELECT t.id, calc.random_bias, 1.0, 0, 1.0, calc.random_bias, 1 FROM topics AS t INNER JOIN (SELECT id, RANDOM() as random_bias FROM topics) AS calc ON calc.id = t.id 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, random_bias, random_multiplier, days_ago_bias, days_ago_multiplier, score, hot_topic_type) SELECT t.id, t.category_id, calc.random_bias, 0.05, calc.days_ago_bias, 0.95, (calc.random_bias * 0.05) + (days_ago_bias * 0.95), 2 FROM topics AS t INNER JOIN (SELECT id, RANDOM() as random_bias, ((1.0 - (EXTRACT(EPOCH FROM CURRENT_TIMESTAMP-created_at)/86400) / :days_ago) * 0.95) AS days_ago_bias FROM topics) AS calc ON calc.id = t.id 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, random_bias, random_multiplier, days_ago_bias, days_ago_multiplier, score, hot_topic_type) SELECT t.id, t.category_id, calc.random_bias, :max_old_score, 0, 1.0, calc.random_bias * :max_old_score, 3 FROM topics AS t INNER JOIN (SELECT id, RANDOM() as random_bias FROM topics) AS calc ON calc.id = t.id 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