This PR improves the performance of the `most_replied_to_users` method on the `UserSummary` model.
### Old Query
```ruby
post_query
.joins(
"JOIN posts replies ON posts.topic_id = replies.topic_id AND posts.reply_to_post_number = replies.post_number",
)
# We are removing replies by @user, but we can simplify this by getting the using the user_id on the posts.
.where("replies.user_id <> ?", @user.id)
.group("replies.user_id")
.order("COUNT(*) DESC")
.limit(MAX_SUMMARY_RESULTS)
.pluck("replies.user_id, COUNT(*)")
.each { |r| replied_users[r[0]] = r[1] }
```
### Old Query with corrections
```ruby
post_query
.joins(
"JOIN posts replies ON posts.topic_id = replies.topic_id AND replies.reply_to_post_number = posts.post_number",
)
# Remove replies by @user but instead look on loaded posts (we do this so we don't count self replies)
.where("replies.user_id <> posts.user_id")
.group("replies.user_id")
.order("COUNT(*) DESC")
.limit(MAX_SUMMARY_RESULTS)
.pluck("replies.user_id, COUNT(*)")
.each { |r| replied_users[r[0]] = r[1] }
```
### New Query
```ruby
post_query
.joins(
"JOIN posts replies ON posts.topic_id = replies.topic_id AND posts.reply_to_post_number = replies.post_number",
)
# Only include regular posts in our joins, this makes sure we don't have the bloat of loading private messages
.joins(
"JOIN topics ON replies.topic_id = topics.id AND topics.archetype <> 'private_message'",
)
# Only include visible post types, so exclude posts like whispers, etc
.joins(
"AND replies.post_type IN (#{Topic.visible_post_types(@user, include_moderator_actions: false).join(",")})",
)
.where("replies.user_id <> posts.user_id")
.group("replies.user_id")
.order("COUNT(*) DESC")
.limit(MAX_SUMMARY_RESULTS)
.pluck("replies.user_id, COUNT(*)")
.each { |r| replied_users[r[0]] = r[1] }
```
# Conclusion
`most_replied_to_users` was untested, so I introduced a test for the logic, and have confirmed that it passes on both the new query **AND** the old query.
Thank you @danielwaterworth for the debugging assistance.
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