Use this skill when writing aggregation pipelines, grouping, joining collections, or optimizing slow MongoDB queries. Trigger words: 集計, aggregate, パイプライン, $group, $lookup, $match, 結合, グループ化, 遅いクエリ, explain.
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$lookup)するとき。find では取れない加工済みデータが欲しいとき。$match と $project をできるだけ前に置く。$match をインデックスが効く形(先頭で等価条件)にする。$lookup は件数を絞ってから。N+1 を避けるが、巨大結合は分割も検討。.explain('executionStats') で IXSCAN を確認。COLLSCAN は赤信号。$match / $project を最前段に置きデータ量を減らす。.explain('executionStats') で IXSCAN 確認を習慣化。$match を最後に置いて全件処理してから絞る。$where / 演算子オブジェクトに展開しない。// ロール別の月間投稿数(直近 30 日)
const since = new Date(Date.now() - 30 * 864e5);
const rows = await PostModel.aggregate([
{ $match: { createdAt: { $gte: since } } }, // 先に絞る(インデックス)
{ $group: { _id: '$authorId', count: { $sum: 1 } } },
{ $sort: { count: -1 } },
{ $limit: 20 },
{ $lookup: { from: 'users', localField: '_id', foreignField: '_id', as: 'author' } },
{ $project: { count: 1, 'author.name': 1 } }, // 必要列だけ
]);
$match し、全件を集計してから捨てる。$lookup で巨大コレクションを無制限結合してメモリ超過。explain を見ずに「動いたから OK」とする。No reviews yet. Tell others what you thought.
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Use this skill when creating or reviewing Next.js Route Handlers (app/api), adding rate limiting, input validation, or auth to API endpoints. Trigger words: API ルート, Route Handler, app/api, エンドポイント, レート制限, 入力検証, CORS, ヘッダー, 認証付き API, hardening.
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Use this skill when implementing full-text search, autocomplete, or vector/semantic search and RAG with MongoDB Atlas. Trigger words: 全文検索, あいまい検索, オートコンプリート, ベクトル検索, セマンティック検索, 類似検索, Atlas Search, $search, $vectorSearch, RAG, embedding.
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Use this skill when implementing sign-in, sessions, authorization checks, or protecting routes and Server Actions. Trigger words: 認証, ログイン, サインイン, セッション, 認可, 権限チェック, Better Auth, Auth.js, 保護, ミドルウェア, getSession.
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Use this skill when starting a new session, opening this project for the first time, or when you need to recall the project's tech stack, hard rules, and which other skills exist. Trigger words: セッション開始, このプロジェクト, 全体像, どのスキル, 何から, getting started, overview.
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Use this skill when setting up or modifying CI pipelines, GitHub Actions workflows, or automated checks (lint, typecheck, test, build) for this project. Trigger words: CI, GitHub Actions, ワークフロー, パイプライン, 自動テスト, lint チェック, typecheck, ビルド検証, .github/workflows.
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Use this skill when writing end-to-end tests, browser automation, or verifying user flows in a real browser. Trigger words: E2E, Playwright, ブラウザテスト, ユーザーフロー, 結合テスト, シナリオテスト, ログインテスト, getByRole, expect.
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