[20190401]那个更快的疑问.txt

--//前一阵子,做了11g于10g下,单表单条记录唯一索引扫描的测试,摘要如下:
--//参考链接:
http://blog.itpub.net/267265/viewspace-2636321/
http://blog.itpub.net/267265/viewspace-2636342/

1.环境:
--//当时的测试,在11g下测试结果如下:
SCOTT@book> select method,count(*),round(avg(TIME_ELA),0),sum(TIME_ELA) from job_times group by method order by 3 ;
METHOD                 COUNT(*) ROUND(AVG(TIME_ELA),0) SUM(TIME_ELA)
-------------------- ---------- ---------------------- -------------
result_cache                 50                   8611        430536
id=1_unique_index            50                   9494        474714
null                         50                  10664        533197
id=1_index                   50                  28160       1407987
notnull                      50                  29279       1463928

--//在10g下测试结果如下:
SCOTT@test> select method,count(*),round(avg(TIME_ELA),0),sum(TIME_ELA) from job_times group by method order by 3 ;
METHOD                 COUNT(*) ROUND(AVG(TIME_ELA),0) SUM(TIME_ELA)
-------------------- ---------- ---------------------- -------------
id=1_unique_index            50                   4864        243192
notnull                      50                  34134       1706713
id=1_index                   50                  34703    &