"goodness knows" meaning in English

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  "lang": "English",
  "lang_code": "en",
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          "word": "God knows"
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      "examples": [
        {
          "ref": "1951, C. S. Lewis, Prince Caspian: The Return to Narnia",
          "text": "We mustn't waste the battery: goodness knows how often we shall need it.",
          "type": "quotation"
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      "glosses": [
        "Alternative form of God knows"
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          "God knows",
          "God knows#English"
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      "related": [
        {
          "word": "my goodness"
        },
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          "word": "oh my goodness"
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  "word": "goodness knows"
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      "expansion": "goodness knows",
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  "lang": "English",
  "lang_code": "en",
  "pos": "phrase",
  "related": [
    {
      "word": "my goodness"
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      "word": "oh my goodness"
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        {
          "word": "God knows"
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        {
          "ref": "1951, C. S. Lewis, Prince Caspian: The Return to Narnia",
          "text": "We mustn't waste the battery: goodness knows how often we shall need it.",
          "type": "quotation"
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        "Alternative form of God knows"
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