AlterQuery  t_mutation_defaults (children 3)
 ExpressionList (children 1)
  AlterCommand UPDATE (children 2)
   Function greater (children 1)
    ExpressionList (children 2)
     Identifier x
     Literal UInt64_0
   ExpressionList (children 1)
    Assignment z (children 1)
     Identifier y
 Identifier t_mutation_defaults
 Set
