# PostAlerter job hangs/OOMs as of late

**URL:** <https://meta.discourse.org/t/postalerter-job-hangs-ooms-as-of-late/270183>\
**Category:** Bug\
**Created:** [June 30, 2023, 5:38pm UTC](https://meta.discourse.org/t/postalerter-job-hangs-ooms-as-of-late/270183 "2023-06-30T17:38:39Z")\
**Posts on this page:** 1\
**Showing post:** 9

<div class="post-metadata">

**Author:** ![kris.kotlarek](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/kris.kotlarek/32/176919_2.png) [@kris.kotlarek](https://meta.discourse.org/u/kris.kotlarek)\
**Post date:** [July 13, 2023, 1:38am UTC](https://meta.discourse.org/t/postalerter-job-hangs-ooms-as-of-late/270183/9 "2023-07-13T01:38:32Z")

</div>

I just merged another try to improve performance of this job:

[https://github.com/discourse/discourse/pull/22487](https://github.com/discourse/discourse/pull/22487)

I tested in on few instances and it was fine, but they were smaller than yours.

If it is still failing with this commit, could you provide me `EXPLAIN ANALYSE` report? Script to generate it:

```ruby
topic = Topic.last
user_option_sql_fragment =
  if SiteSetting.watched_precedence_over_muted
    <<~SQL
    INTERSECT
    SELECT user_id FROM user_options WHERE user_options.watched_precedence_over_muted IS false
    SQL
  else
    <<~SQL
    EXCEPT
    SELECT user_id FROM user_options WHERE user_options.watched_precedence_over_muted IS true
    SQL
  end
user_ids_sql = <<~SQL
  (
    SELECT user_id FROM category_users WHERE category_id = #{topic.category_id.to_i} AND notification_level = #{CategoryUser.notification_levels[:muted]}
    UNION
    SELECT user_id FROM tag_users tu JOIN topic_tags tt ON tt.tag_id = tu.tag_id AND tt.topic_id = #{topic.id} WHERE tu.notification_level = #{TagUser.notification_levels[:muted]}
    EXCEPT
    SELECT user_id FROM topic_users tus WHERE tus.topic_id = #{topic.id} AND tus.notification_level = #{TopicUser.notification_levels[:watching]}
  )
  #{user_option_sql_fragment}
SQL
sql = User.where("id IN (#{user_ids_sql})").to_sql

sql_with_index = <<SQL
EXPLAIN ANALYZE #{sql};
SQL
result = ActiveRecord::Base.connection.execute("#{sql_with_index}")
puts sql_with_index
result.each do |r|
  puts r.values
end

```

It would help me to find missing index or which part of this query is so slow.

---

_[View the full topic](https://meta.discourse.org/t/postalerter-job-hangs-ooms-as-of-late/270183)._