JSONColumns

Documentação do formato JSONColumns

Entrada	Saída	Alias
✔	✔

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Descrição

A saída dos formatos JSONColumns* fornece o nome do campo no ClickHouse e, em seguida, o conteúdo de cada linha da tabela para esse campo; visualmente, os dados são rotacionados 90 graus para a esquerda.

Neste formato, todos os dados são representados como um único objeto JSON.

O formato JSONColumns mantém todos os dados em memória e depois os gera como um único bloco, portanto isso pode levar a um alto consumo de memória.

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Exemplo de uso

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Inserção de dados

Usando um arquivo JSON com os dados a seguir, chamado football.json:

{
    "date": ["2022-04-30", "2022-04-30", "2022-04-30", "2022-05-02", "2022-05-02", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07"],
    "season": [2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021],
    "home_team": ["Sutton United", "Swindon Town", "Tranmere Rovers", "Port Vale", "Salford City", "Barrow", "Bradford City", "Bristol Rovers", "Exeter City", "Harrogate Town A.F.C.", "Hartlepool United", "Leyton Orient", "Mansfield Town", "Newport County", "Oldham Athletic", "Stevenage Borough", "Walsall"],
    "away_team": ["Bradford City", "Barrow", "Oldham Athletic", "Newport County", "Mansfield Town", "Northampton Town", "Carlisle United", "Scunthorpe United", "Port Vale", "Sutton United", "Colchester United", "Tranmere Rovers", "Forest Green Rovers", "Rochdale", "Crawley Town", "Salford City", "Swindon Town"],
    "home_team_goals": [1, 2, 2, 1, 2, 1, 2, 7, 0, 0, 0, 0, 2, 0, 3, 4, 0],
    "away_team_goals": [4, 1, 0, 2, 2, 3, 0, 0, 1, 2, 2, 1, 2, 2, 3, 2, 3]
}

Insira os dados:

INSERT INTO football FROM INFILE 'football.json' FORMAT JSONColumns;

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Leitura de dados

Leia os dados usando o formato JSONColumns:

SELECT *
FROM football
FORMAT JSONColumns

A saída será em formato JSON:

{
    "date": ["2022-04-30", "2022-04-30", "2022-04-30", "2022-05-02", "2022-05-02", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07", "2022-05-07"],
    "season": [2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021, 2021],
    "home_team": ["Sutton United", "Swindon Town", "Tranmere Rovers", "Port Vale", "Salford City", "Barrow", "Bradford City", "Bristol Rovers", "Exeter City", "Harrogate Town A.F.C.", "Hartlepool United", "Leyton Orient", "Mansfield Town", "Newport County", "Oldham Athletic", "Stevenage Borough", "Walsall"],
    "away_team": ["Bradford City", "Barrow", "Oldham Athletic", "Newport County", "Mansfield Town", "Northampton Town", "Carlisle United", "Scunthorpe United", "Port Vale", "Sutton United", "Colchester United", "Tranmere Rovers", "Forest Green Rovers", "Rochdale", "Crawley Town", "Salford City", "Swindon Town"],
    "home_team_goals": [1, 2, 2, 1, 2, 1, 2, 7, 0, 0, 0, 0, 2, 0, 3, 4, 0],
    "away_team_goals": [4, 1, 0, 2, 2, 3, 0, 0, 1, 2, 2, 1, 2, 2, 3, 2, 3]
}

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Configurações de formato

Durante a importação, colunas com nomes desconhecidos serão ignoradas se a configuração input_format_skip_unknown_fields estiver definida como 1. As colunas que não estiverem presentes no bloco serão preenchidas com valores padrão (aqui, você pode usar a configuração input_format_defaults_for_omitted_fields)