anchor.diff:  import PostgreKeyword, DataType, Keyword, PostgreBase, BaseRule, Symbol;
   
   alterTable
  -    : alterTableNameWithAsterisk (alterTableActions| renameColumn | renameConstraint)
  +    : alterTableNameWithAsterisk (alterTableActions | renameColumn | renameConstraint)
       | alterTableNameExists renameTable
       ;
   
  
positive.code:     | ALTER CONSTRAINT constraintName constraintOptionalParam
      | VALIDATE CONSTRAINT constraintName
      | DROP CONSTRAINT (IF EXISTS)? constraintName (RESTRICT | CASCADE)?
      | INHERIT tableName
      | NO INHERIT tableName
      | REPLICA IDENTITY (DEFAULT | USING INDEX indexName | FULL | NOTHING)
      ;
  
  tableConstraintUsingIndex
  
negative.code:     : RENAME CONSTRAINT constraintName TO constraintName
      ;
  
  storageParameterWithValue
      : storageParameter EQ_OR_ASSIGN simpleExpr
      ;
  
  storageParameter
      : ID
      ;
  
  alterTableNameExists
      : alterTableOp (IF EXISTS)? tableName
      ;
  