セッションの分離性レベルを変更、確認する方法

SQL> alter session set isolation_level = READ COMMITTED;

Session altered.

SQL> select sid, name, isdefault, value from V$SES_OPTIMIZER_ENV where name like '%isolation%' and sid = (select sys_context('USERENV', 'SID') from dual);

       SID NAME                           ISD VALUE
---------- -------------------------------------------------- --- -------------------------
       289 transaction_isolation_level               YES read_commited

SQL> alter session set isolation_level = SERIALIZABLE;

Session altered.

SQL> select sid, name, isdefault, value from V$SES_OPTIMIZER_ENV where name like '%isolation%' and sid = (select sys_context('USERENV', 'SID') from dual);

       SID NAME                           ISD VALUE
---------- -------------------------------------------------- --- -------------------------
       289 transaction_isolation_level               NO  serializable