QueryDoctor

QueryDoctor is a local-first CLI that diagnoses slow PostgreSQL queries and validates potential index fixes using HypoPG before applying anything to production.

What it does

For the top slow statements in pg_stat_statements, QueryDoctor:

1. Sanitizes parameterized SQL
2. Runs EXPLAIN (FORMAT JSON)
3. Detects likely root causes (seq scans, wildcard LIKE, sorts)
4. Simulates an index with HypoPG
5. Compares planner cost before/after
6. Prints recommended SQL + confidence

Requirements

• Node.js 18+
• PostgreSQL with:
  • pg_stat_statements
  • hypopg
• DATABASE_URL set in your environment

Install

npm install

Run

DATABASE_URL=postgres://user:pass@localhost:5432/dbname npm start

Or after linking globally:

npm link
querydoctor

Safety

• QueryDoctor does not create real indexes.
• It only creates hypothetical indexes (hypopg_create_index) and resets them (hypopg_reset).
• It performs read-only diagnosis queries and EXPLAIN plans.