anchor.diff:  import PostgreKeyword, DataType, Keyword, PostgreBase, BaseRule, Symbol;
   
   alterTable
  -    : alterTableNameWithAsterisk (alterTableActions| renameColumn | renameConstraint)
  +    : alterTableNameWithAsterisk (alterTableActions | renameColumn | renameConstraint)
       | alterTableNameExists renameTable
       ;
   
  
positive.code:     ;
       
  modifyColumn
      : alterColumn (SET DATA)? TYPE dataType collateClause? (USING simpleExpr)?
      ;
       
  alterColumn     
      : ALTER COLUMN? columnName
      ;
       
  alterTableAddConstraint       
  
negative.code:     | ALTER CONSTRAINT constraintName constraintOptionalParam
      | VALIDATE CONSTRAINT constraintName
      | DROP CONSTRAINT (IF EXISTS)? constraintName (RESTRICT | CASCADE)?
      | (DISABLE |ENABLE) TRIGGER (triggerName | ALL | USER )?
      | ENABLE (REPLICA | ALWAYS) TRIGGER triggerName
      | (DISABLE | ENABLE) RULE rewriteRuleName
      | ENABLE (REPLICA | ALWAYS) RULE rewriteRuleName
      | (DISABLE | ENABLE | (NO? FORCE)) ROW LEVEL SECURITY
      | CLUSTER ON indexName
      | SET WITHOUT CLUSTER
      | SET (WITH | WITHOUT) OIDS
      | SET TABLESPACE tablespaceName
      | SET (LOGGED | UNLOGGED)
      | SET LEFT_PAREN storageParameterWithValue (COMMA storageParameterWithValue)* RIGHT_PAREN
      | RESET LEFT_PAREN storageParameter (COMMA storageParameter)* RIGHT_PAREN
      | INHERIT tableName
      | NO INHERIT tableName
      | OF typeName
      | NOT OF
      | OWNER TO (ownerName | CURRENT_USER | SESSION_USER)
      | REPLICA IDENTITY (DEFAULT | (USING INDEX indexName) | FULL | NOTHING)
      ;
  
  tableConstraintUsingIndex
  