How to get call stack of oracle processes ?
Each time your program performs a function call, information about the call is generated. That information includes the location of the call in your program, the arguments of the call, and the local variables ..
Script: Display the sessions distribution and top 50 idle sessions
This script displays the top 50 longest idle times and list distribution of sessions on the instance..
I prefer the version 11.2.0.3 parse_calls (我比较喜欢parse_calls在11203版本上的显示)
高parse calls表示这些SQL不可以re-used 并且每次执行都要重新解析，理想的最佳状态是一次解析多次执行，你也知道频繁的解析会给library cache带来沉重的负担， 一个sql的执行必须先parse，解析过程包含sql 加载到shared pool, 语法检查…
Logon Storms on 11g ,audit maybe cause performance issue.(当创建很多连接时审计可能带来性能问题)
When multiple connection created will insert a lot of rows in aud$ table, there may be contention in the segment header for the table. This contention can manifest itself as a buffer busy wait or a freelist wait.
