{
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  "as_of": "2026-10-23",
  "item": {
    "id": "METHOD-0270",
    "kind": "METHOD",
    "title": "DuckDBのwindow関数でグループ内の順位を付ける",
    "last_verified": "2026-10-23",
    "currentness": "VERIFIED_AS_OF",
    "revision": 1,
    "requirements": [
      "対象ファイルへの権限",
      "型・文字コードの確認",
      "原典と導入済みversionの対応を確認し、権限のある検証用入力・別の出力先を用意する"
    ],
    "suitable_for": "グループごとの上位候補を抽出する場面。",
    "unsuitable_for": "順序を指定せず再現可能な順位を求める用途。",
    "purpose": "DuckDBのwindow関数でグループ内の順位を付ける",
    "composition": "DuckDB",
    "shortest_path": [
      "区分キー・並び順と同順位の規則を決める",
      "PARTITION BYとORDER BYを指定して順位を計算する",
      "同値とNULLを含む結果を照合する"
    ],
    "verification": "row_numberとrankの違いを確認し、必要な順序が一意になることを検査します。",
    "coverage": [
      "database/SQL",
      "data transformation"
    ],
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    "ads": "OFF",
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