SQL Query Optimizer

Analyze and rewrite slow SQL queries for better performance with explanations of every optimization made.

Prompt Template

You are a database performance expert. Analyze and optimize the following SQL query:

Database: [e.g., PostgreSQL, MySQL, SQLite]
Query:
```sql
[paste your query here]
```

Table schemas (if relevant):
[paste CREATE TABLE statements or describe columns]

Current problem: [e.g., takes 8 seconds on 2M rows, causes timeouts]
Existing indexes: [list them if known]

Provide:
1. Analysis of why the query is slow
2. Optimized query (with comments)
3. Recommended indexes to add
4. Explanation of each change made
5. Estimated improvement (rough %)

Example Output

Analysis

The query performs a full table scan on `orders` (2M rows) because:

- `WHERE status = 'pending'` filters on an unindexed column

- The `JOIN` on `users.email` uses a non-indexed string column

- `SELECT *` fetches unnecessary columns, increasing I/O

Optimized Query

SELECT o.id, o.total, o.created_at, u.name

FROM orders o

INNER JOIN users u ON u.id = o.user_id -- join on indexed integer FK

WHERE o.status = 'pending'

AND o.created_at > NOW() - INTERVAL '30 days'

ORDER BY o.created_at DESC

LIMIT 100;

Recommended Indexes

CREATE INDEX idx_orders_status_created ON orders(status, created_at DESC);

Changes Made

- Replaced `JOIN ON email` with `JOIN ON user_id` (integer FK, much faster)

- Added date range filter to reduce result set before sorting

- Replaced `SELECT *` with specific columns

**Estimated improvement:** 15x–40x faster with the composite index.

Tips for Best Results

💡Always run EXPLAIN ANALYZE before and after to measure actual improvement
💡Composite indexes should have the most selective column first
💡Never optimize prematurely — profile first, then fix the actual bottleneck

Try it with

ChatGPT Claude

Frequently Asked Questions

What is the SQL Query Optimizer prompt?

Analyze and rewrite slow SQL queries for better performance with explanations of every optimization made. It's a free ChatGPT prompt template from our Coding collection — copy it, fill in the bracketed variables, and paste it into your AI tool.

Which AI tools work with this prompt?

It's written and tested for ChatGPT and Claude. Any AI assistant that accepts free-form text prompts will handle it well.

How do I customize this ChatGPT prompt?

Replace the bracketed variables — such as [e.g., PostgreSQL, MySQL, SQLite], [paste your query here], [list them if known] — with your own details before running it. Always run EXPLAIN ANALYZE before and after to measure actual improvement

Is this prompt free to use?

Yes. Every prompt on PromptAtlas is free to copy, customize, and use — no signup required.

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