今天分析awr报告时候用到的wait class部分的解释：

Idle Waits: Whenever an Oracle process has no work to do this is an idle wait. For most processes this is because they are waiting on the user to provide a new SQL statement to execute.

Application: These are waits caused by the way the application is designed. These include row lock waits, and table or other locks that are requested by the application either explicitly or implicitly (possibly due to DDL).

Configuration: These are waits which occur in a badly configured system and weill be reduced dramatically as a result of proper tuning.

Administrative: These are waits imposed by a privileged users by some action.

Concurrency: These are waits that can not be tuned and will occur on a system with High Concurrency.

Commit: This class only has log file sync. It deserves a special class because it is a necessary event and will be high and is supposed to be high on a system doing queries.

Network: All waits due to network messaging delays belong here. They are supposed to point out network congestion or latency. They should not include think or processing time, only the time spent in the networking code and hardware.

User I/O Waits: All waits for Disk I/O done by User queries or even SMON, MMON

System I/O Waits: All waits for Disk I/O done by backgrnd processes like LGWR, DBWR, ARCH, RFS. But not SMON and MMON

Scheduler: These are waits due to the resource manager

Cluster: waits which will occur only in RAC mode.

Other: All the wait events, which do not fit into one of the above classes clearly, or are not important to classify. By not important I mean those that wait for an insignificant amount of time or really do not fit into any one class.