Cannot find the Session Identifier

相信有一部分初学者，在用普通用户做执行计划分析的时候会遇到如下错误
SQL> set autotrace on
SP2-0618: Cannot find the Session Identifier. Check PLUSTRACE role is enabled
SP2-0611: Error enabling STATISTICS report
SQL> select * from v$version;
BANNER
----------------------------------------------------------------
Oracle Database 10g Enterprise Edition Release 10.1.0.2.0 - Prod
PL/SQL Release 10.1.0.2.0 - Production
CORE 10.1.0.2.0 Production
TNS for 32-bit Windows: Version 10.1.0.2.0 - Production
NLSRTL Version 10.1.0.2.0 - Production

看提示是说PLUSTRACE role is not enabled
数据库在安装的时候没有创建plustrace 角色
该角色有那些权限？
我们可以从ora_homesqlplusadminplustrce.sql中找到答案
-- Copyright (c) Oracle Corporation 1995, 2002. All Rights Reserved.
--
-- NAME
-- plustrce.sql
--
-- DESCRIPTION
-- Creates a role with access to Dynamic Performance Tables
-- for the SQL*Plus SET AUTOTRACE ... STATISTICS command.
-- After this script. has been run, each user requiring access to
-- the AUTOTRACE feature should be granted the PLUSTRACE role by
-- the DBA.
--
-- USAGE
-- sqlplus "/ as sysdba" @plustrce
--
-- Catalog.sql must have been run before this file is run.
-- This file must be run while connected to a DBA schema.
set echo on
drop role plustrace;
create role plustrace;
grant select on v_$sesstat to plustrace;
grant select on v_$statname to plustrace;
grant select on v_$mystat to plustrace;
grant plustrace to dba with admin option;
set echo off
至此我们可以利用该sql脚本创建plustrace role
SQL> show user
USER is "SYS"
SQL> @?sqlplusadminplustrce
SQL>
SQL> drop role plustrace;
Role dropped.
SQL> create role plustrace;
Role created.
SQL>
SQL> grant select on v_$sesstat to plustrace;
Grant succeeded.
SQL> grant select on v_$statname to plustrace;
Grant succeeded.
SQL> grant select on v_$mystat to plustrace;
Grant succeeded.
SQL> grant plustrace to dba with admin option;
Grant succeeded.
SQL>
SQL> set echo off
SQL> grant plustrace to scott;
Grant succeeded.
你可以将该role授予任何用户
然后我们再用scott用户连上看看
C:>sqlplus scott/tiger
SQL*Plus: Release 10.1.0.2.0 - Production on Wed May 24 11:36:43 2006
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> select count(*) from tt;
COUNT(*)
----------
1
SQL> set autotrace traceonly
SQL> select count(*) from tt;

Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT ptimizer=ALL_ROWS (Cost=3 Card=1)
1 0 SORT (AGGREGATE)
2 1 TABLE ACCESS (FULL) OF 'TT' (TABLE) (Cost=3 Card=1)

Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
7 consistent gets
0 physical reads
0 redo size
393 bytes sent via SQL*Net to client
512 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processed
至此这一问题得到解决