Skill Introduction

Overview

PostgreSQL database patterns for query optimization, schema design, indexing, and security. Based on Supabase best practices.

Core value

Turns reusable Development know-how into an installable skill, helping users complete github, community work faster.

Target users

Developers, testers, and maintainers who handle Development tasks in Focus Code.
Teams that already trust workflows or content from affaan-m.
Users who want standardized prompts, steps, or conventions instead of repeating setup work.

Best practices

Read the skill content first to confirm required inputs, expected outputs, and dependencies.
Try it on a small task before relying on it for critical work.
Add project-specific constraints such as coding style, target platform, test expectations, and delivery format.
For external sources, verify the source link, version, and recent maintenance activity.

Best use cases

Tasks related to github, community that need a reusable execution flow.
Converting a community repo, team convention, or personal workflow into day-to-day assistance.
Starting from a proven skill instead of writing prompts or procedures from scratch.

Limits and boundaries

Results depend on the quality of the original skill content and may need human correction.
It does not replace code review, tests, security review, or professional judgment.
External tools, APIs, account permissions, and local dependencies still need separate setup.

Differentiation

Structured around Development, making it easier to discover and reuse than loose prompt snippets.
Marked as GitHub, which helps users judge trust and maintenance expectations.
Keeps the original source link available for repository, documentation, or discussion follow-up.
Tagged with github, community, so it can be filtered by concrete task intent.

Install and use

Install

Copy Install Command

focus install postgres-patterns-1687a9

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SKILL.md

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name: postgres-patterns description: PostgreSQL database patterns for query optimization, schema design, indexing, and security. Based on Supabase best practices.

PostgreSQL パターン

PostgreSQLベストプラクティスのクイックリファレンス。詳細なガイダンスについては、database-reviewer エージェントを使用してください。

起動タイミング

SQLクエリまたはマイグレーションの作成時
データベーススキーマの設計時
低速クエリのトラブルシューティング時
Row Level Securityの実装時
コネクションプーリングの設定時

クイックリファレンス

インデックスチートシート

クエリパターン	インデックスタイプ	例
`WHERE col = value`	B-tree（デフォルト）	`CREATE INDEX idx ON t (col)`
`WHERE col > value`	B-tree	`CREATE INDEX idx ON t (col)`
`WHERE a = x AND b > y`	複合	`CREATE INDEX idx ON t (a, b)`
`WHERE jsonb @> '{}'`	GIN	`CREATE INDEX idx ON t USING gin (col)`
`WHERE tsv @@ query`	GIN	`CREATE INDEX idx ON t USING gin (col)`
時系列範囲	BRIN	`CREATE INDEX idx ON t USING brin (col)`

データタイプクイックリファレンス

用途	正しいタイプ	避けるべき
ID	`bigint`	`int`、ランダムUUID
文字列	`text`	`varchar(255)`
タイムスタンプ	`timestamptz`	`timestamp`
金額	`numeric(10,2)`	`float`
フラグ	`boolean`	`varchar`、`int`

一般的なパターン

複合インデックスの順序:

-- 等価列を最初に、次に範囲列
CREATE INDEX idx ON orders (status, created_at);
-- 次の場合に機能: WHERE status = 'pending' AND created_at > '2024-01-01'

カバリングインデックス:

CREATE INDEX idx ON users (email) INCLUDE (name, created_at);
-- SELECT email, name, created_at のテーブル検索を回避

部分インデックス:

CREATE INDEX idx ON users (email) WHERE deleted_at IS NULL;
-- より小さなインデックス、アクティブユーザーのみを含む

RLSポリシー（最適化）:

CREATE POLICY policy ON orders
  USING ((SELECT auth.uid()) = user_id);  -- SELECTでラップ！

UPSERT:

INSERT INTO settings (user_id, key, value)
VALUES (123, 'theme', 'dark')
ON CONFLICT (user_id, key)
DO UPDATE SET value = EXCLUDED.value;

カーソルページネーション:

SELECT * FROM products WHERE id > $last_id ORDER BY id LIMIT 20;
-- O(1) vs OFFSET は O(n)

キュー処理:

UPDATE jobs SET status = 'processing'
WHERE id = (
  SELECT id FROM jobs WHERE status = 'pending'
  ORDER BY created_at LIMIT 1
  FOR UPDATE SKIP LOCKED
) RETURNING *;

アンチパターン検出

-- インデックスのない外部キーを検索
SELECT conrelid::regclass, a.attname
FROM pg_constraint c
JOIN pg_attribute a ON a.attrelid = c.conrelid AND a.attnum = ANY(c.conkey)
WHERE c.contype = 'f'
  AND NOT EXISTS (
    SELECT 1 FROM pg_index i
    WHERE i.indrelid = c.conrelid AND a.attnum = ANY(i.indkey)
  );

-- 低速クエリを検索
SELECT query, mean_exec_time, calls
FROM pg_stat_statements
WHERE mean_exec_time > 100
ORDER BY mean_exec_time DESC;

-- テーブル肥大化をチェック
SELECT relname, n_dead_tup, last_vacuum
FROM pg_stat_user_tables
WHERE n_dead_tup > 1000
ORDER BY n_dead_tup DESC;

設定テンプレート

-- 接続制限（RAMに応じて調整）
ALTER SYSTEM SET max_connections = 100;
ALTER SYSTEM SET work_mem = '8MB';

-- タイムアウト
ALTER SYSTEM SET idle_in_transaction_session_timeout = '30s';
ALTER SYSTEM SET statement_timeout = '30s';

-- モニタリング
CREATE EXTENSION IF NOT EXISTS pg_stat_statements;

-- セキュリティデフォルト
REVOKE ALL ON SCHEMA public FROM public;

SELECT pg_reload_conf();

postgres patterns