{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "#/components/schemas/UniqueKey",
  "title": "UniqueKey",
  "allOf": [
    {
      "$ref": "#/components/schemas/Constraint"
    }
  ],
  "type": "object",
  "description": "Unique keys are columns in a table that uniquely identify items in the rows. This sounds a lot like a primary key, but the main difference is that unique keys can have NULL values."
}