Postgres Patterns Skill for Claude

-- 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'

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

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

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

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

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

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 *;

-- 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;

-- 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();