[新版]依据不合的绑定变量的值来选择不合的履行计划测试.doc

[新版]依据不合的绑定变量的值来选择不合的履行计划测试根据不同的绑定变量的值来选择不同的执行计划测试adaptivecursorsharing功能实现了根据不同的绑定变量的值来选择不同的执行计划测试个人分类:;altersystemflushbuffer_cache;=ALL_ROWS;altersessionsetoptimizer_index_cost_adj=100;altersessionsetoptimizer_index_caching=0;;createtablet(idnumber,namevarchar2(30));insertintotselectmod(rownum,2),object_namefromall_objects;insertintotselect2,'test'fromdual;createindext_indont(id);(user,'T',cascade=>true,method_opt=>'forcolumnsidsize254');,count(*)cntfromtgroupbyid;SQL>selectid,count(*)cnt2fromt3groupbyid;T--------------------17033921070338selectcount(*)cntfromt;SQL>selectcount(*)T----------140678Theselectivityofcolumnidvalue"2":1/140678="1":70339/140678="0":70338/140678=:varv_idnumber;exec:v_id:=0;setlines200columnPLAN_TABLE_OUTPUTformata100selectcount(name)fromtwhereid=:v_id;select*fromtable();SQL>select*fromtable();PLAN_TABLE_OUTPUT----------------------------------------------------------------------------------------------------SQL_IDgsmm31bu4zyca,childnumber0-------------------------------------selectcount(name)fromtwhereid=:v_idPlanhashva