A PostgreSQL 16+ reference for PostgreSQL, a database system that stores structured application data and lets you query it with SQL. It covers queries, table design, indexes, and performance tuning.

Use it to write or optimize queries, create or change tables, inspect running queries, and investigate database performance.

It helps choose suitable SQL, data types, indexes, and diagnostic commands instead of guessing why a query or schema is slow or incorrect.

postgresql — Skill by jgamaraalv

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/jgamaraalv/ts-dev-kit/postgresql

Any agent

npx skills add jgamaraalv/ts-dev-kit --skill postgresql

Clone the repo

git clone --depth 1 https://github.com/jgamaraalv/ts-dev-kit

Made for: Claude Code, Codex.

Per session 151 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 820 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.

Model	Per session	Once invoked
Fable 5	$0.00151	$0.00820
Opus 5	$0.00076	$0.00410
Sonnet 5	$0.00030	$0.00164
Haiku 4.5	$0.00015	$0.00082

Measured 2d ago against content hash a232fd34062c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

postgresql 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/postgresql/SKILL.md · 63 lines

How it starts

The opening of the file, as written. The whole thing — 63 lines — stays where its author put it; the contents beside it link to each section on GitHub.

PostgreSQL 16+ Reference

Version: 16+. All syntax is standard; most features apply to PostgreSQL 13+.

<quick_reference>

Quick patterns

-- Check running queries
SELECT pid, state, wait_event_type, query FROM pg_stat_activity WHERE state != 'idle';

-- Explain a slow query
EXPLAIN (ANALYZE, BUFFERS, FORMAT TEXT) SELECT ...;

-- List table sizes
SELECT relname, pg_size_pretty(pg_total_relation_size(oid)) FROM pg_class
WHERE relkind = 'r' ORDER BY pg_total_relation_size(oid) DESC;

-- Kill a blocking query
SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE pid = <pid>;

</quick_reference>

Key non-obvious facts

Every statement runs in a transaction. Without BEGIN, each statement auto-commits.
jsonb stores parsed binary (faster queries); json stores raw text (exact input preserved). Prefer jsonb.
LIKE 'foo%' can use B-tree; LIKE '%foo' cannot — use pg_trgm GIN for suffix search.
CREATE INDEX CONCURRENTLY avoids table lock but cannot run inside a transaction block.
EXPLAIN without ANALYZE shows the planner's estimate. Always use EXPLAIN (ANALYZE, BUFFERS) for real data.
Null values are stored in indexes by B-tree (unlike some other databases). IS NULL can use an index.
SERIAL/BIGSERIAL are shorthand for sequence + default; prefer GENERATED ALWAYS AS IDENTITY (SQL standard).
Default isolation level is Read Committed. SERIALIZABLE prevents all anomalies but may abort transactions.

Reference files

Load the relevant file when working on a specific topic:

Topic	File	When to read
SELECT, JOINs, CTEs, window functions	references/queries.md	Writing or debugging any query
CREATE TABLE, ALTER TABLE, constraints	references/ddl-schema.md	Designing or modifying schemas
Index types, creation, strategy	references/indexes.md	Adding indexes or fixing slow queries
Transactions, savepoints, isolation	references/transactions.md	Concurrency, locking, isolation issues
JSONB operators, GIN, jsonpath	references/jsonb.md	Working with JSON/JSONB columns
EXPLAIN output, VACUUM, stats	references/performance.md	Query tuning or performance analysis
psql meta-commands	references/psql-cli.md	Working interactively in psql

Read the full file on GitHub · 63 lines

Files

What ships with it

7 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.

2d ago First seen · 63 lines · 151 tokens per session scan A a232fd34062c

Subscribe to this mod's changes

postgresql is a skill published in the GitHub repository jgamaraalv/ts-dev-kit (15 stars, last pushed 6mo ago), licensed MIT. It adds 151 tokens to every session and 820 once invoked, about $0.0008 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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