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lax

strict

Automatic unnesting of arrays

Certain path steps, such as the member accessor $.key, automatically iterate over SQL/JSON sequences. To make these iterative path steps friendlier for arrays, arrays are automatically unnested prior to performing the iterative path step. This means that the user does not need to use an explicit [*] to unnest an array prior to performing an iterative path step. This facilitates the use case where a field may be either an array or a scalar.

Arrays are not automatically unnested (the user can still write [*] to unnest an array explicitly).

Automatic wrapping within an array

Subscript path steps, such as $[0] or $[*], may be applied to a non-array. To do this, the non-array is implicitly wrapped in an array prior to applying the subscript operation. This also facilitates the use case where a field may be either an array or a scalar.

There is no automatic wrapping prior to subscript path steps.

Error han- dling

Many errors related to whether data is or is not an array or scalar are handled by the two preceding features. The remain- ing errors are classified as either struc- tural or non-structural. An example of a structural error is $.name if $ has no member whose key is name. Structural errors are converted to empty SQL/JSON sequences. An example of a non-struc- tural error is divide by zero; such errors are not elided.

Errors are strictly defined in all cases

OPERATOR

RESULT

JSON_OBJECT('id', 87, 'name', 'carrot')

{"id": 87, "name": "carrot"} 

JSON_ARRAY(1, "abc", NULL, TRUE)

[1, "abc", null, true]

o_id

attribute

value

2

color

red

2

fabric

silk

3

color

green

3

shape

square