Query optimizer

Skill m-binimran/dev-pack/skills/query-optimizer

Guardrails, skills, loops, hooks & review agents for database + website builders on Claude Code (Next.js + Supabase).

Install

npx -y skills add m-binimran/dev-pack --skill query-optimizer

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

One thing to look at

2 stars2 stars. Stars are a popularity signal and not a quality one, but at this level it is likely that nobody has read this closely except its author, and you would be relying on your own review.

What its author says it does

Copied from the file, not written here

Diagnose and fix slow Postgres queries using EXPLAIN ANALYZE, index suggestions, and N+1 detection. Use when a query is slow, a page is slow because of the DB, or before shipping a query that touches a large table.

SKILL.md

1.5 KB, as published. Nobody here has run it

query-optimizer

Make the query fast based on evidence, not guesses.

Process

Get the plan: run EXPLAIN (ANALYZE, BUFFERS) <query>. Never optimize without it.
Read the plan top-down: find the costliest node. Look for:
- Seq Scan on a big table where an index could be used.
- Rows Removed by Filter high → missing/!selective index.
- Estimated vs actual rows far apart → stale stats (ANALYZE).
- Nested loop over many rows → maybe a hash/merge join is better.
Propose the smallest fix: an index, a rewritten predicate, a LIMIT, or pagination.
Re-measure with EXPLAIN ANALYZE and report before/after timing. Don't claim a win without it.

Common fixes

Composite index ordered by selectivity for multi-column filters.
Partial index (where active) for queries that always filter the same way.
Replace OFFSET pagination with keyset (where id > $last) for deep pages.
Kill N+1: one query per row in app code → use a join or IN (...)/= ANY.

Output

The plan's bottleneck in one sentence.
The fix (SQL/DDL).
Before/after timing from real EXPLAIN ANALYZE runs.

Guardrails

An index isn't free — it slows writes. Only add what the plan justifies.
Don't add an index that duplicates an existing one's prefix.