【问题分类】性能优化，功能使用

【关键字】outline

【问题描述】防止SQL执行计划突变，用outline固化执行计划

【问题原因分析】防止SQL执行计划突变，用outline固化执行计划

【解决/规避方法】

SQL--创建测试outline：ol_ab/ol_baconn sales/salesCREATE OUTLINE ol_ab FOR CATEGORY ctgy_ab ONSELECT /*+ leading(a,b) */ a.area_name, b.branch_nameFROM area a, branches bWHERE a.area_no = b.area_noAND b.branch_no LIKE '01%'AND a.area_no LIKE '01';CREATE OUTLINE ol_ba FOR CATEGORY ctgy_ab ONSELECT a.area_name, b.branch_nameFROM area a, branches bWHERE a.area_no = b.area_noAND b.branch_no LIKE '01%'AND a.area_no LIKE '01';--修改基表，交换outlineconn / as sysdbaUPDATE OL$HINTS SET OL_NAME=DECODE(OL_NAME,'OL_AB','OL_BA','OL_BA','OL_AB') WHERE OL_NAME IN ('OL_AB','OL_BA');--打开outline开关ALTER SESSION SET USE_STORED_OUTLINES=ctgy_ab;--验证应用SQL执行计划conn sales/salesexplain SELECT a.area_name, b.branch_nameFROM area a, branches bWHERE a.area_no = b.area_noAND b.branch_no LIKE '01%'AND a.area_no LIKE '01';

【影响范围】严重降低SQL执行效率

【修复版本】22.2