commit: 5be9d139816fa40ff6227950b58f3c6cea01fc81
parent a0c9a2b4cc8c22d6238b0f31239c1e655f47730f
Author: faried nawaz <faried@gmail.com>
Date: Wed, 21 Apr 2021 03:52:32 +0500
a better query to delete from hashtags
old query:
Delete on hashtags (cost=5089.81..5521.63 rows=6160 width=18)
-> Hash Semi Join (cost=5089.81..5521.63 rows=6160 width=18)
Hash Cond: (hashtags.id = ht.id)
-> Seq Scan on hashtags (cost=0.00..317.28 rows=17528 width=14)
-> Hash (cost=5012.81..5012.81 rows=6160 width=20)
-> Merge Anti Join (cost=0.70..5012.81 rows=6160 width=20)
Merge Cond: (ht.id = hto.hashtag_id)
-> Index Scan using hashtags_pkey on hashtags ht (cost=0.29..610.53 rows=17528 width=14)
-> Index Scan using hashtags_objects_pkey on hashtags_objects hto (cost=0.42..3506.48 rows=68158 width=14)
new query:
Delete on hashtags ht (cost=0.70..5012.81 rows=6160 width=12)
-> Merge Anti Join (cost=0.70..5012.81 rows=6160 width=12)
Merge Cond: (ht.id = hto.hashtag_id)
-> Index Scan using hashtags_pkey on hashtags ht (cost=0.29..610.53 rows=17528 width=14)
-> Index Scan using hashtags_objects_pkey on hashtags_objects hto (cost=0.42..3506.48 rows=68158 width=14)
Diffstat:
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/lib/mix/tasks/pleroma/database.ex b/lib/mix/tasks/pleroma/database.ex
@@ -97,12 +97,10 @@ defmodule Mix.Tasks.Pleroma.Database do
|> Repo.delete_all(timeout: :infinity)
prune_hashtags_query = """
- delete from hashtags
- where id in (
- select id from hashtags as ht
- left join hashtags_objects as hto
- on hto.hashtag_id = ht.id
- where hto.hashtag_id is null)
+ delete from hashtags as ht
+ where not exists (
+ select 1 from hashtags_objects hto
+ where ht.id = hto.hashtag_id)
"""
Repo.query(prune_hashtags_query)