prompt

SQL Query Optimizer

Analyzes a slow SQL query and suggests indexes, rewrites, and plan improvements.

VettedUpdated June 2026

The prompt

You are a database performance engineer. Analyze and optimize the {{engine}} query below.

Inputs:
- Engine: {{engine}} (PostgreSQL, MySQL, etc.)
- The slow query: {{query}}
- Table sizes / known indexes: {{context}}

Produce:
1. The likely bottleneck (full scan, missing index, N+1, bad join order, function on an indexed column).
2. A concrete rewrite of {{query}} if structure is the issue, with the change explained.
3. Index recommendations (exact CREATE INDEX statements), and which columns/order and why.
4. What to check in EXPLAIN/EXPLAIN ANALYZE to confirm the win.
5. One caution (index write cost, selectivity, or stale stats).

Rules: use valid {{engine}} syntax; don't recommend indexes blindly \u2014 tie each to a predicate or join in the query; note when the real fix is schema or app-side, not the query.

Did it work? Rate this prompt

Variables

{{engine}}Database engine

{{query}}Slow query

{{context}}Table sizes / indexes

Example output

Engine: PostgreSQL. Query filters orders by status and a date range, then sorts by created_at. Table: 5M rows, only PK index. Bottleneck: a sequential scan on orders \u2014 the WHERE on status + created_at has no supporting index, and the ORDER BY adds a sort. Index: CREATE INDEX idx_orders_status_created ON orders (status, created_at DESC); Status first (equality predicate), created_at second (range + sort) \u2014 this lets Postgres seek by status then read created_at in order, satisfying both filter and ORDER BY. Confirm in EXPLAIN ANALYZE: you want an Index Scan (not Seq Scan) and no separate Sort node. Caution: this index adds write cost on a high-insert table; if status has few distinct values, its selectivity is low \u2014 verify the date range is what makes it selective.

Details

Author

AI Khazna

License

—

Security

Vetted

Type

prompt

Frequently asked questions

What is the SQL Query Optimizer prompt?

Analyzes a slow SQL query and suggests indexes, rewrites, and plan improvements.

Is SQL Query Optimizer free?

Yes, it is free to use.

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