Index for refresh_tokens on deletion by user_id not used properly

[kevcodez]

Bug report

• I confirm this is a bug with Supabase, not with my own application.
• I confirm I have searched the Docs, GitHub Discussions, and Discord.

Describe the bug

When investigating slow query logs in our database, we found that supabase_auth_admin accounts for the absolute majority of slow queries. One of the slow queries was the deletion of refresh_tokens by user_id.

Looking at the table definition, there is an index on instance_id + user_id. As the instance_id field is not part of the query, it seems to significantly slow down the queries.

Without instance id (35ms)

explain analyze delete from auth.refresh_tokens where user_id = 'd9e8a26c-5a31-43e8-833a-9fcb7ceda191' 

Delete on refresh_tokens (cost=0.43..13318.67 rows=0 width=0) (actual time=34.693..34.693 rows=0 loops=1)
-> Index Scan using refresh_tokens_instance_id_user_id_idx on refresh_tokens (cost=0.43..13318.67 rows=31 width=6) (actual time=34.691..34.691 rows=0 loops=1)
Index Cond: ((user_id)::text = 'd9e8a26c-5a31-43e8-833a-9fcb7ceda191'::text)
Planning Time: 1.229 ms
Execution Time: 34.876 ms

With instance id (0.271ms)

Delete on refresh_tokens (cost=0.43..17.68 rows=0 width=0) (actual time=0.095..0.095 rows=0 loops=1)
-> Index Scan using refresh_tokens_instance_id_user_id_idx on refresh_tokens (cost=0.43..17.68 rows=31 width=6) (actual time=0.094..0.094 rows=0 loops=1)
Index Cond: ((instance_id = '00000000-0000-0000-0000-000000000000'::uuid) AND ((user_id)::text = 'd9e8a26c-5a31-43e8-833a-9fcb7ceda191'::text))
Planning Time: 1.192 ms
Execution Time: 0.271 ms

Screenshots

[travis-humata]

Looks similar to this issue I found with recovery_token index #1398

[J0]

closing as this has been deployed - let us know if there are still issues though