PERF: base importer updates user_stats with sql (mostly)

script/import_scripts/base.rb

@@ -49,6 +49,7 @@ class ImportScripts::Base
     update_bumped_at
     update_last_posted_at
     update_last_seen_at
+    update_user_stats
     update_feature_topic_users
     update_category_featured_topics
     update_topic_count_replies
@@ -568,6 +569,71 @@ class ImportScripts::Base
     User.exec_sql(sql)
   end
 
+  def update_user_stats
+    puts "", "Updating topic reply counts..."
+    User.find_each do |u|
+      u.create_user_stat if u.user_stat.nil?
+      us = u.user_stat
+      us.update_topic_reply_count
+      us.save
+      print "."
+    end
+
+    puts "Updating first_post_created_at..."
+
+    sql = <<-SQL
+      WITH sub AS (
+        SELECT user_id, MIN(posts.created_at) AS first_post_created_at
+        FROM posts
+        GROUP BY user_id
+      )
+      UPDATE user_stats
+      SET first_post_created_at = sub.first_post_created_at
+      FROM user_stats u1
+      JOIN sub ON sub.user_id = u1.user_id
+      WHERE u1.user_id = user_stats.user_id
+        AND user_stats.first_post_created_at <> sub.first_post_created_at
+    SQL
+
+    User.exec_sql(sql)
+
+    puts "Updating user post_count..."
+
+    sql = <<-SQL
+      WITH sub AS (
+        SELECT user_id, COUNT(*) AS post_count
+        FROM posts
+        GROUP BY user_id
+      )
+      UPDATE user_stats
+      SET post_count = sub.post_count
+      FROM user_stats u1
+      JOIN sub ON sub.user_id = u1.user_id
+      WHERE u1.user_id = user_stats.user_id
+        AND user_stats.post_count <> sub.post_count
+    SQL
+
+    User.exec_sql(sql)
+
+    puts "Updating user topic_count..."
+
+    sql = <<-SQL
+      WITH sub AS (
+        SELECT user_id, COUNT(*) AS topic_count
+        FROM topics
+        GROUP BY user_id
+      )
+      UPDATE user_stats
+      SET topic_count = sub.topic_count
+      FROM user_stats u1
+      JOIN sub ON sub.user_id = u1.user_id
+      WHERE u1.user_id = user_stats.user_id
+        AND user_stats.topic_count <> sub.topic_count
+    SQL
+
+    User.exec_sql(sql)
+  end
+
   # scripts that are able to import last_seen_at from the source data should override this method
   def update_last_seen_at
     puts "", "updating last seen at on users"