Database Indexing Prompts

My [app / Django app / Rails app / Node app] has a page that loads slowly: [describe the page, e.g. "the orders list filtered by customer" or "the search results page"].

The table has [number] rows and growing. Find the slow query, explain why it's slow, and add a database index to fix it.

After adding the index:
- Show me the before and after query speed difference
- Explain what the index does in plain English
- Tell me if I need to run a migration or any extra step

My stack: [your language and framework here, e.g. Python + Django, Ruby on Rails, Node + PostgreSQL]

I'm learning, so explain each part simply.

I want to find slow database queries in my Django app before users complain.

Set up Django Debug Toolbar so I can:
- See every SQL query each page runs
- See how long each query takes
- Spot queries doing full table scans (sequential scans)
- Identify which queries would benefit from an index

Walk me through the installation, settings, and what to look for once it's running.

My Django version: [your version, e.g. Django 4.2]

I'm learning, so explain each part simply.

My [app] has grown and I want to make sure I'm not missing important database indexes.

Review my models/schema and:
- List every column that appears in WHERE, ORDER BY, or JOIN clauses
- Identify which of those columns are missing indexes
- Recommend composite (multi-column) indexes for queries that filter on multiple fields at once
- Flag any indexes I already have that might be unnecessary or redundant
- Prioritize the fixes by biggest performance impact

My stack: [your language and framework here]
Here are my models/schema: [paste your models or schema file]

I'm learning, so explain each part simply.