oracle 对比sql语句执行环境-优快云博客

由于执行环境，
子游标无法共享

SQL> select distinct sid from v$mystat;

SID
----------
132

SQL> select distinct sid from v$mystat;

SID
----------
130
SQL> alter session set optimizer_mode=first_rows_10;(130)

Session altered.

SQL> select count(*) from t1;(sid 132)

COUNT(*)
----------
1999

select b.inst_id,b.sql_id,b.child_number.b.plaN_hash_value from gv$sql b where b.sql_text='select count(*) from t1'

#
set linesize 1000
select a.inst_id,b.sql_id ,b.sql_text,b.hash_value,b.child_number,b.plan_hash_value from gv$session a ,gv$sql b where a.sid=&sid and b.hash_value in (a.prev_hash_value)
and a.inst_id=b.inst_id;

SQL> show user
USER is "SYS"
SQL>
SQL> select b.sql_id ,b.sql_text,b.hash_value,b.child_number,b.plan_hash_value from v$session a ,v$sql b where a.sid=&sid and b.hash_value in (a.sql_hash_value,a.prev_hash_value);

SQL_ID        SQL_TEXT                                 HASH_VALUE CHILD_NUMBER
------------- ---------------------------------------- ---------- ------------
PLAN_HASH_VALUE
---------------
5bc0v4my7dvr5 select count(*) from t1                  4235652837            0
     3724264953

SQL> select count(*) from t1;(130)

COUNT(*)
----------
      1999
SQL> select b.sql_id ,b.sql_text,b.hash_value,b.child_number,b.plan_hash_value from v$session a ,v$sql b where a.sid=&sid and b.hash_value in (a.sql_hash_value,a.prev_hash_value);
Enter value for sid: 130
old   1: select b.sql_id ,b.sql_text,b.hash_value,b.child_number,b.plan_hash_value from v$session a ,v$sql b where a.sid=&sid and b.hash_value in (a.sql_hash_value,a.prev_hash_value)
new   1: select b.sql_id ,b.sql_text,b.hash_value,b.child_number,b.plan_hash_value from v$session a ,v$sql b where a.sid=130 and b.hash_value in (a.sql_hash_value,a.prev_hash_value)

5bc0v4my7dvr5 select count(*) from t1 4235652837 1
3724264953

执行计划一样，plan_hash_value可以看出来，但确产生了不同的子游标

SELECT name, value, default_value
FROM v$sys_optimizer_env
WHERE isdefault = 'NO';

#查环境变量哪个不是默认的，针对当前session修改过
SELECT name, value
FROM v$ses_optimizer_env
WHERE sid = 161 AND isdefault = 'NO'
MINUS
SELECT name, value
FROM v$sys_optimizer_env;

#查看2个不同session环境变量
SQL> SELECT e0.name, e0.value AS value_child_0, e1.value AS value_child_1
2   FROM v$sql_optimizer_env e0, v$sql_optimizer_env e1
3   WHERE e0.sql_id = e1.sql_id
4   AND e0.sql_id = '&sql_id'
5   AND e0.child_number = 0
6   AND e1.child_number = 1
7   AND e0.name = e1.name
8   AND e0.value <> e1.value;

NAME VALUE_CHILD_0
---------------------------------------- -------------------------
VALUE_CHILD_1
-------------------------
optimizer_mode all_rows
first_rows_10

SELECT e0.inst_id,e0.name, e0.value AS value_child_0, e1.inst_id,e1.value AS value_child_1
   FROM gv$sql_optimizer_env e0, gv$sql_optimizer_env e1
    WHERE e0.sql_id = e1.sql_id
     AND e0.sql_id = '&sql_id'
    AND e0.child_number = 0
    AND e1.child_number = 1
    AND e0.name = e1.name
    AND e0.value <> e1.value;

来自 “ ITPUB博客 ” ，链接：http://blog.itpub.net/12020513/viewspace-665125/，如需转载，请注明出处，否则将追究法律责任。

转载于:http://blog.itpub.net/12020513/viewspace-665125/