在sqlplus中set autotrace on 出错的解决办法（ Unable to verify PLAN_TABLE）

在做sql语句的性能优化时执行set autotrace on时出错．特记下解决过程，分享给大家，也方便自己以后查看
1。出错

SQL> set autotrace on exp
SP2-0613: Unable to verify PLAN_TABLE format or existence
SP2-0611: Error enabling EXPLAIN report

2。解决（红色为输入）

SQL*Plus: Release 10.1.0.2.0 - Production on 星期二 1月 12 15:00:56 2010
Copyright (c) 1982, 2004, Oracle.  All rights reserved.
Connected to:
Oracle Database 10g Enterprise Edition Release 10.1.0.2.0 - Production
With the Partitioning, OLAP and Data Mining options
SQL> @$ORACLE_HOME/rdbms/admin/utlxplan

Table created.

SQL> create public synonym plan_table for plan_table;

Synonym created.

SQL> grant all on plan_table to public ;
Grant succeeded.

SQL> @$ORACLE_HOME/sqlplus/admin/plustrce SQL>
SQL> drop role plustrace;
drop role plustrace
          *
ERROR at line 1:
ORA-01919: role 'PLUSTRACE' does not exist

SQL> create role plustrace;

Role created.

SQL>
SQL> grant select on v_$sesstat to plustrace;

Grant succeeded.

SQL> grant select on v_$statname to plustrace;

Grant succeeded.

SQL> grant select on v_$session to plustrace;

Grant succeeded.

SQL> grant plustrace to dba with admin option;

Grant succeeded.

SQL>
SQL> set echo off
SQL> grant plustrace to public ;

Grant succeeded.

SQL>

3。做完上面操作就好了，