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11g by User rowid Performance

原创 Linux操作系统 作者:yyp2009 时间:2012-05-07 21:08:42 0 删除 编辑
得 到现在 还没有11g过
不过哥都被你们忽悠了!我个人观点如下:
不过rowid访问 自然是最快的

1 table access by user rowid

2 table access by user index rowid
在访问表时效率差不多的
而两者差别就在 如果有同样的rowid 访问有两次 rowid会更快(top p296)
而同样的访问11g会在result cache中保存说不定,说不定11g快就是这个原因!而10g没有resultcache!
呵呵!
 
Rowid Access
The most efficient way to access a row is to directly specify its rowid in the WHERE clause. However,
to take advantage of that access path, you have to get the rowid first, store it, and then reuse it
for further accesses. In other words, it is a method that can be considered only if a row is accessed
at least two times.
However,
to get the rowid first, store it will be 11g rc!so why rowid access quick swift fast 10g rowid access。
 
this is it!
 
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