Format Settings

SereneDB can attempt to determine the format of a JSON file when setting format to auto. Here are some example JSON files and the corresponding format settings that should be used.

In each of the below cases, the format setting was not needed, as SereneDB was able to infer it correctly, but it is included for illustrative purposes. A query of this shape would work in each case:

Query

SELECT *FROM filename.json;

Result

 key1   | key2--------+-------- value1 | value1 value2 | value2 value3 | value3

Format: newline_delimited

With format = 'newline_delimited' newline-delimited JSON can be parsed. Each line is a JSON.

We use the example file records.json with the following content:

{"key1":"value1", "key2": "value1"}
{"key1":"value2", "key2": "value2"}
{"key1":"value3", "key2": "value3"}

Query

SELECT *FROM read_json('records.json', format = 'newline_delimited');

Result

 key1   | key2--------+-------- value1 | value1 value2 | value2 value3 | value3

Format: array

If the JSON file contains a JSON array of objects (pretty-printed or not), array may be used. To demonstrate its use, we use the example file records-in-array.json:

[
    { "key1": "value1", "key2": "value1" },
    { "key1": "value2", "key2": "value2" },
    { "key1": "value3", "key2": "value3" }
]

Query

SELECT *FROM read_json('records-in-array.json', format = 'array');

Result

 key1   | key2--------+-------- value1 | value1 value2 | value2 value3 | value3

Format: unstructured

If the JSON file contains JSON that is not newline-delimited or an array, unstructured may be used. To demonstrate its use, we use the example file unstructured.json:

{
    "key1":"value1",
    "key2":"value1"
}
{
    "key1":"value2",
    "key2":"value2"
}
{
    "key1":"value3",
    "key2":"value3"
}

Query

SELECT *FROM read_json('unstructured.json', format = 'unstructured');

Result

 key1   | key2--------+-------- value1 | value1 value2 | value2 value3 | value3

records Options

SereneDB can attempt to determine whether a JSON file contains records when setting records = auto. When records = true, SereneDB expects JSON objects, and will unpack the fields of JSON objects into individual columns.

Continuing with the same example file, records.json:

{"key1":"value1", "key2": "value1"}
{"key1":"value2", "key2": "value2"}
{"key1":"value3", "key2": "value3"}

Query

SELECT *FROM read_json('records.json', records = true);

Result

 key1   | key2--------+-------- value1 | value1 value2 | value2 value3 | value3

When records = false, SereneDB will not unpack the top-level objects, and create STRUCTs instead:

Query

SELECT *FROM read_json('records.json', records = false);

Result

 json----------------- (value1,value1) (value2,value2) (value3,value3)

This is especially useful if we have non-object JSON, for example, arrays.json:

[1, 2, 3]
[4, 5, 6]
[7, 8, 9]

Query

SELECT *FROM read_json('arrays.json', records = false);

Result

 json--------- {1,2,3} {4,5,6} {7,8,9}