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86 lines
3.2 KiB
Markdown
86 lines
3.2 KiB
Markdown
# JSON
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Outputs data in JSON format. Besides data tables, it also outputs column names and types, along with some additional information: the total number of output rows, and the number of rows that could have been output if there weren't a LIMIT. Example:
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```sql
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SELECT SearchPhrase, count() AS c FROM test.hits GROUP BY SearchPhrase WITH TOTALS ORDER BY c DESC LIMIT 5 FORMAT JSON
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```
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```json
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{
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"meta":
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[
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{
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"name": "SearchPhrase",
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"type": "String"
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},
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{
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"name": "c",
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"type": "UInt64"
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}
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],
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"data":
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[
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{
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"SearchPhrase": "",
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"c": "8267016"
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},
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{
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"SearchPhrase": "bathroom interior design",
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"c": "2166"
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},
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{
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"SearchPhrase": "yandex",
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"c": "1655"
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},
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{
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"SearchPhrase": "spring 2014 fashion",
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"c": "1549"
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},
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{
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"SearchPhrase": "freeform photos",
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"c": "1480"
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}
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],
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"totals":
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{
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"SearchPhrase": "",
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"c": "8873898"
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},
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"extremes":
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{
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"min":
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{
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"SearchPhrase": "",
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"c": "1480"
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},
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"max":
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{
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"SearchPhrase": "",
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"c": "8267016"
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}
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},
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"rows": 5,
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"rows_before_limit_at_least": 141137
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}
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```
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The JSON is compatible with JavaScript. To ensure this, some characters are additionally escaped: the slash ` /` is escaped as ` \/`; alternative line breaks ` U+2028` and ` U+2029`, which break some browsers, are escaped as ` \uXXXX`. ASCII control characters are escaped: backspace, form feed, line feed, carriage return, and horizontal tab are replaced with `\b`, `\f`, `\n`, `\r`, `\t` , as well as the remaining bytes in the 00-1F range using `\uXXXX` sequences. Invalid UTF-8 sequences are changed to the replacement character <20> so the output text will consist of valid UTF-8 sequences. For compatibility with JavaScript, Int64 and UInt64 integers are enclosed in double quotes by default. To remove the quotes, you can set the configuration parameter output_format_json_quote_64bit_integers to 0.
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`rows` – The total number of output rows.
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`rows_before_limit_at_least` The minimal number of rows there would have been without LIMIT. Output only if the query contains LIMIT.
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If the query contains GROUP BY, rows_before_limit_at_least is the exact number of rows there would have been without a LIMIT.
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`totals` – Total values (when using WITH TOTALS).
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`extremes` – Extreme values (when extremes is set to 1).
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This format is only appropriate for outputting a query result, but not for parsing (retrieving data to insert in a table).
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See also the JSONEachRow format.
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