What is pg-slow-query-diagnosis?

A guided process for finding why PostgreSQL database queries are slow by examining query statistics, execution plans, indexes, and table information.

Use it to investigate slow queries, high latency, timeouts, resource-heavy database work, and possible index improvements.

It turns a broad performance problem into a structured investigation and produces specific optimization suggestions.

pg-slow-query-diagnosis — Skill for Claude Code and Codex by isdaniel

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.

Any agent

npx skills add isdaniel/pgtuner_mcp --skill pg-slow-query-diagnosis

Clone the repo

git clone --depth 1 https://github.com/isdaniel/pgtuner_mcp

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/isdaniel/pgtuner_mcp/pg-slow-query-diagnosis/github.svg)](https://agentmods.dev/skills/isdaniel/pgtuner_mcp/pg-slow-query-diagnosis)

Your own site

<a href="https://agentmods.dev/skills/isdaniel/pgtuner_mcp/pg-slow-query-diagnosis"><img src="https://agentmods.dev/badge/skills/isdaniel/pgtuner_mcp/pg-slow-query-diagnosis/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/isdaniel/pgtuner_mcp/pg-slow-query-diagnosis"><img src="https://agentmods.dev/badge/skills/isdaniel/pgtuner_mcp/pg-slow-query-diagnosis.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,128 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00052	$0.03128
Opus 5.5	$0.00021	$0.01251
Sonnet 5.5	$0.00010	$0.00626
Haiku 4.5	$0.00005	$0.00313

Measured 2mo ago against content hash 8ac3fbe307f1, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

pg-slow-query-diagnosis 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 2mo 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/pg-slow-query-diagnosis/SKILL.md · 295 lines

How it starts

The opening of the file, as written. The whole thing — 295 lines — stays where its author put it; the contents beside it link to each section on GitHub.

PostgreSQL Slow Query Diagnosis

This skill guides systematic diagnosis and optimization of slow queries in PostgreSQL databases using the pgtuner-mcp server tools.

When to Use This Skill

Use this skill when the user:

Reports slow queries or poor query performance
Asks "why is my query slow?" or "how can I speed up this query?"
Wants to find and fix the top resource-consuming queries
Mentions high query latency, timeouts, or slow API responses
Asks to investigate pg_stat_statements data

MCP Resources Available

Before calling tools, the agent can read lightweight resources for quick context:

pgtuner://docs/tools -- Full tool reference documentation
pgtuner://docs/workflows -- Recommended workflow patterns
pgtuner://query/{query_hash}/stats -- Detailed stats for a specific query by queryid (from get_slow_queries output)
pgtuner://table/{schema}/{table_name}/stats -- Quick table statistics without running the full tool
pgtuner://table/{schema}/{table_name}/indexes -- Indexes on a specific table

This skill corresponds to the diagnose_slow_queries MCP Prompt and partially to query_tuning. If the user triggers either prompt, follow this skill's workflow.

Prerequisites

The pgtuner-mcp server must be connected with a valid DATABASE_URI
Required: pg_stat_statements extension (check availability early -- if missing, tool will return an error)
Optional: hypopg extension for hypothetical index testing
Optional: pglast library on the server for SQL parsing in index recommendations

Pre-Flight Checks

Before starting the workflow, verify extension availability:

If get_slow_queries returns an error about pg_stat_statements, inform the user it must be enabled and provide setup instructions.
If the user wants hypothetical index testing, use manage_hypothetical_indexes with action: "check" to verify HypoPG is available. If not, skip Step 4 and rely on heuristic recommendations.

Read the full file on GitHub · 295 lines

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.

2mo ago First seen · 295 lines · 52 tokens per session scan A 8ac3fbe307f1

Subscribe to this mod's changes

pg-slow-query-diagnosis is a skill published in the GitHub repository isdaniel/pgtuner_mcp (30 stars, last pushed 5mo ago), licensed Apache-2.0. It adds 52 tokens to every session and 3,128 once invoked, about $0.0002 per session on Opus 5.5. 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.

Databases Debugging PostgreSQL ai mcp-server python3

pg-slow-query-diagnosis next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
pg-slow-query-diagnosisisdaniel/pgtuner_mcp	Skill	30	5mo ago	Apache-2.0	A	52	Claude Code, Codex
exasol-mcp-serverexasol/mcp-server	Skill	18	2d ago	MIT	A	36	Claude Code, Codex
tencent-pg-slowquery-diagnosisTencentCloudCommunity/mcp-server	Skill	32	3mo ago	Apache-2.0	A	75	Claude Code, Codex
amazon aurora dsqlawslabs/mcp	Skill	9.9k	yesterday	Apache-2.0	A	46	Claude Code
sql-optimizerMathews-Tom/armory	Skill	340	5d ago	MIT	A	78	Claude Code
profiling-slow-api-endpointsPostHog/posthog	Skill	41k	today	none	A	113	Claude Code, Codex
ecto-constraint-debugoliver-kriska/claude-elixir-phoenix	Skill	574	yesterday	MIT	A	36	Claude Code