1---
2title: Clear, Action-Oriented Title (e.g., "Use Partial Indexes for Filtered Queries")
3impact: MEDIUM
4impactDescription: 5-20x query speedup for filtered queries
5tags: indexes, query-optimization, performance
6---
7 
8## [Rule Title]
9 
10[1-2 sentence explanation of the problem and why it matters. Focus on performance impact.]
11 
12**Incorrect (describe the problem):**
13 
14```sql
15-- Comment explaining what makes this slow/problematic
16CREATE INDEX users_email_idx ON users(email);
17 
18SELECT * FROM users WHERE email = '[email protected]' AND deleted_at IS NULL;
19-- This scans deleted records unnecessarily
20```
21 
22**Correct (describe the solution):**
23 
24```sql
25-- Comment explaining why this is better
26CREATE INDEX users_active_email_idx ON users(email) WHERE deleted_at IS NULL;
27 
28SELECT * FROM users WHERE email = '[email protected]' AND deleted_at IS NULL;
29-- Only indexes active users, 10x smaller index, faster queries
30```
31 
32[Optional: Additional context, edge cases, or trade-offs]
33 
34Reference: [Postgres Docs](https://www.postgresql.org/docs/current/)
35