# Database performance notes (Supabase linter)

This project had two performance-related linter groups:

1. **RLS auth function evaluation**
2. **Unindexed foreign keys**

## What was changed

1. Added migration `infrastructure/migrations/002_perf_linter_fixes.sql`.
2. Updated `infrastructure/migrations/001_schema.sql` to keep fresh setups aligned with the same fixes.

### RLS changes

The affected policies now use:

- `(select auth.uid())` instead of `auth.uid()`

This avoids repeated per-row evaluation in RLS plans for these policies:

- `profiles_update`
- `posts_select`
- `posts_insert`
- `posts_update_own`
- `resonances_insert`
- `resonances_delete`
- `whispers_select`
- `whispers_insert`
- `follows_insert`
- `follows_delete`
- `reports_insert`
- `reports_select_own`

Also, duplicate permissive update policies on `public.posts` were consolidated by removing `posts_softdelete` and keeping a single `posts_update_own`.

### FK index changes

Added covering indexes:

- `idx_follows_following_id` on `public.follows(following_id)`
- `idx_reports_reporter_id` on `public.reports(reporter_id)`
- `idx_resonances_user_id` on `public.resonances(user_id)`
- `idx_whispers_from_user_id` on `public.whispers(from_user_id)`
- `idx_whispers_post_id` on `public.whispers(post_id)`

## About "unused index" findings

`unused_index` is based on `pg_stat_user_indexes.idx_scan`, which can read as zero after restarts or during low traffic.  
In this environment, PostgreSQL was recently restarted, so these were not dropped automatically.

Suggested review query:

```sql
select
  schemaname,
  relname as table_name,
  indexrelname as index_name,
  idx_scan
from pg_stat_user_indexes
where schemaname = 'public'
order by idx_scan asc, indexrelname;
```

Drop an index only after observing sustained zero usage over representative production traffic.