sql-query-optimizer

A guide for finding why SQL database queries run slowly and for improving their queries, indexes, and execution plans. An execution plan shows how the database intends to retrieve the data.

In plain words
What is it for?
Use it to investigate high CPU or memory use, slow joins and reports, pagination problems, deadlocks, and lock contention, then rewrite queries or recommend indexes.
Why use it?
It helps locate problems such as reading an entire table, using unsuitable indexes, inefficient joins, or competing database locks.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/codebygarv/ai-skills/sql-query-optimizer
Any agent
npx skills add codebygarv/Ai-skills --skill sql-query-optimizer
Clone the repo
git clone --depth 1 https://github.com/codebygarv/Ai-skills

Made for: Claude Code, Codex.

Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 363 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00024 $0.00363
Opus 5 $0.00012 $0.00181
Sonnet 5 $0.00005 $0.00073
Haiku 4.5 $0.00002 $0.00036

Measured 2d ago against content hash 9c3fa0d4d0ec, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

sql-query-optimizer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/development/sql-query-optimizer/SKILL.md · 35 lines

What it actually says

Purpose

Analyze slow or resource-intensive SQL queries, interpret EXPLAIN / ANALYZE execution plans, and rewrite queries or recommend precise indexes to eliminate sequential scans and lock contention.

When to Use

  • A query causes high CPU, memory pressure, or connection saturation on the database.
  • Designing complex joins, aggregations, window functions, or subqueries.
  • Diagnosing deadlocks or table lock contention under concurrent writes.

What to Analyze

  1. Execution Plan: Inspect cost nodes, Seq Scans, Index Scans, Bitmap Index Scans, Nested Loops vs Hash Joins.
  2. Predicate SARGability: Identify functions on indexed columns (e.g. WHERE DATE(created_at) = ...) preventing index hits.
  3. Join & Subquery Efficiency: Convert correlated subqueries to CTEs, Window Functions, or Hash Joins.
  4. Indexing Strategy: Single-column, composite (ordering column matches query pattern), partial, or covering indexes.
  5. Pagination Mechanics: Replace large offset pagination (OFFSET 100000) with keyset/cursor pagination.

Output Format

  • Diagnosis: Why the query is slow (missing index, scan type, cardinality misestimate).
  • Optimized SQL: Clean rewritten query with explanation.
  • DDL Changes: Exact CREATE INDEX CONCURRENTLY statements needed.
  • Before vs After Metrics: Expected scan cost reduction and latency impact.

Avoid

  • Adding indexes on every column without considering write throughput degradation.
  • Omitting CONCURRENTLY on production index creation statements.
Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 35 lines · 24 tokens per session scan A 9c3fa0d4d0ec

Subscribe to this mod's changes

sql-query-optimizer is a skill published in the GitHub repository codebygarv/Ai-skills (24 stars, last pushed 12d ago), licensed MIT. It adds 24 tokens to every session and 363 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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