# Reader badge causing performance issues

**URL:** https://meta.discourse.org/t/reader-badge-causing-performance-issues/305416
**Category:** Support
**Tags:** performance
**Created:** [April 25, 2024, 1:08pm UTC](https://meta.discourse.org/t/reader-badge-causing-performance-issues/305416 "2024-04-25T13:08:35Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![RGJ](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/rgj/32/523185_2.png) [@RGJ](https://meta.discourse.org/u/RGJ)
#### Post date: [April 25, 2024, 1:08pm UTC](https://meta.discourse.org/t/reader-badge-causing-performance-issues/305416/1 "2024-04-25T13:08:35Z")

</div>

On multiple of our largest forums it’s always the [same query](https://github.com/discourse/discourse/blame/c62d3610c6915a58a1dc683605d5819cb5577baf/lib/badge_queries.rb#L4-L19) that is causing a high database load: badge 17 (Reader), probably due to the size of `topic_timings`.

The explain looks quite horrendous. I don’t see any obvious performance improvements except for turning off the badge but I thought I’d post here and see if anyone has any ideas.

```plaintext
 Nested Loop Semi Join (cost=1045564.36..1122735.60 rows=1 width=12)
   Join Filter: (users.id = "ANY_subquery".user_id)
   -> Seq Scan on users (cost=0.00..3149.19 rows=29219 width=4)
   -> Materialize (cost=1045564.36..1119148.13 rows=1 width=4)
         -> Subquery Scan on "ANY_subquery" (cost=1045564.36..1119148.12 rows=1 width=4)
               -> GroupAggregate (cost=1045564.36..1119148.11 rows=1 width=12)
                     Group Key: pt.user_id, pt.topic_id, t.posts_count
                     Filter: (count(*) >= t.posts_count)
                     -> Gather Merge (cost=1045564.36..1119148.09 rows=1 width=12)
                           Workers Planned: 2
                           -> Incremental Sort (cost=1044564.34..1118147.95 rows=2 width=12)
                                 Sort Key: pt.user_id, pt.topic_id, t.posts_count
                                 Presorted Key: pt.user_id
                                 -> Merge Left Join (cost=970980.80..1118147.86 rows=1 width=12)
                                       Merge Cond: (pt.user_id = ub.user_id)
                                       Filter: (ub.id IS NULL)
                                       -> Sort (cost=956553.39..967890.72 rows=4534932 width=12)
                                             Sort Key: pt.user_id
                                             -> Nested Loop (cost=67.77..377652.59 rows=4534932 width=12)
                                                   Join Filter: (t_1.id = pt.topic_id)
                                                   -> Nested Loop (cost=67.19..335182.35 rows=4883 width=20)
                                                         -> Hash Join (cost=66.76..58411.29 rows=317 width=12)
                                                               Hash Cond: (t_1.category_id = c.id)
                                                               -> Nested Loop (cost=0.42..58339.78 rows=1847 width=16)
                                                                     -> Parallel Seq Scan on topics t (cost=0.00..42353.02 rows=2030 width=8)
                                                                           Filter: (posts_count > 100)
                                                                     -> Index Scan using forum_threads_pkey on topics t_1 (cost=0.42..7.88 rows=1 width=8)
                                                                           Index Cond: (id = t.id)
                                                                           Filter: ((deleted_at IS NULL) AND visible)
                                                               -> Hash (cost=66.20..66.20 rows=11 width=4)
                                                                     -> Seq Scan on categories c (cost=0.00..66.20 rows=11 width=4)
                                                                           Filter: (allow_badges AND (NOT read_restricted))
                                                         -> Index Scan using index_posts_on_topic_id_and_post_number on posts p (cost=0.43..870.75 rows=234 width=8)
                                                               Index Cond: (topic_id = t_1.id)
                                                               Filter: ((deleted_at IS NULL) AND (post_type = ANY ('{1,2,3}'::integer[])))
                                                   -> Index Only Scan using post_timings_unique on post_timings pt (cost=0.57..8.57 rows=10 width=12)
                                                         Index Cond: ((topic_id = p.topic_id) AND (post_number = p.post_number))
                                       -> Sort (cost=14427.41..14442.29 rows=5955 width=8)
                                             Sort Key: ub.user_id
                                             -> Bitmap Heap Scan on user_badges ub (cost=126.58..14054.03 rows=5955 width=8)
                                                   Recheck Cond: (badge_id = 17)
                                                   -> Bitmap Index Scan on index_user_badges_on_badge_id_and_user_id (cost=0.00..125.09 rows=5955 width=0)
                                                         Index Cond: (badge_id = 17)

```