sql profile固定执行计划(Automatic)
--在我们无法修改源代码的时候,我们可以采用sqlprofile来改变执行计划 --新增一张测试表 create table test_emp as select * from scott.emp; --新建索引 create index idx_001 on test_emp(empno); --下面的语句正常是要走全表扫描的 select /*+ no_index(test_emp idx_001) */ * from test_emp where empno=7521; select * from v$sql t where t.SQL_TEXT like '%select /*+ no_index(test_emp idx_001) */ * from test_emp where empno=7521%' select * from table(dbms_xplan.display_cursor('6xgya67tytkax',0,'ADVANCED ALLSTATS LAST PEEKED_BINDS')); --创建一个调优任务 declare my_task_name varchar2(30); my_sqltext clob; begin my_sqltext:='select /*+ no_index(test_emp idx_001) */ * from test_emp where empno=7499'; my_task_name:=dbms_sqltune.create_tuning_task( sql_text=>my_sqltext, user_name => 'X86', scope=>'COMPREHENSIVE', time_limit=>60, task_name=>'my_sql_tuning_task_2', description=>'Task to tune a query on table test_emp'); end; --执行这个调优任务 begin dbms_sqltune.execute_tuning_task(task_name => 'my_sql_tuning_task_2'); end; --发现有可用的调优方案 select dbms_sqltune.report_tuning_task('my_sql_tuning_task_2') from dual
--应用这个调优方案 begin dbms_sqltune.accept_sql_profile(task_name => 'my_sql_tuning_task_2', task_owner => 'X86', replace => TRUE,force_match => true); end; begin dbms_sqltune.drop_sql_profile('SYS_SQLPROF_01602055212c0000'); dbms_sqltune.drop_tuning_task('my_sql_tuning_task_2'); end;