Check constraints

Check constraints are changed from inside altertable with three keys: add_check, modify_check and drop_check.

A check constraint takes a name and a condition. See Conditions for the condition format.

Add check constraint

add_check takes an array of check constraints.


{
  "altertable": {
    "events": {
      "add_check": [
        {
          "name": "events_valid_time",
          "condition": {
            "type": "comparison",
            "op": ">",
            "left": { "type": "column", "name": "end_at" },
            "right": { "type": "column", "name": "start_at" }
          }
        }
      ]
    }
  }
}

Modify check constraint

modify_check has the same shape as add_check. Because a constraint cannot be changed in place, it is compiled to a drop of the existing constraint (by name) followed by adding it again with the new definition.


{
  "altertable": {
    "events": {
      "modify_check": [
        {
          "name": "events_valid_time",
          "condition": {
            "type": "comparison",
            "op": ">=",
            "left": { "type": "column", "name": "end_at" },
            "right": { "type": "column", "name": "start_at" }
          }
        }
      ]
    }
  }
}

Drop check constraint

drop_check takes an array of constraint names.


{
  "altertable": {
    "events": {
      "drop_check": ["events_valid_time"]
    }
  }
}