Oracle JSON: lax vs strict format

With lax format, the following JSON document is valid. It is invalid with strict format because strict format requires names to be quoted.

{
   num: 42
}

The default format is lax.

The difference between lax and strict JSON format only plays a role when using the two predicates is json and is not json.

The following check constraint makes sure that documents are stored in the strict format:

create table tasks (
  …
  doc varchar(4000) check (doc is json (strict))
);