************************************************************ * Description: Knowledge of Oracle AWR report terminologies * Date: 05:17 PM EST, 06/25/2018 ************************************************************ <1> Oracle AWR report is one of the best methods to understand Operating System performance: | |__ o. The following is the explainantion of part of the concepts within AWR report. <2> Elapsed Time: | |__ o. Elpased Time is the whole physical "Wall Clock" period for a process from start until finish, which including time spend on I/O and CPU. <3> DB Time: | |__ o. If you make a AWR report for 1-hour period, and sometimes you can find "DB Time" is 300 or 1000+ minutes, even multiple times than an hour [60 minutes]. | |__ o. DB Time is the sum of total time, that all sessions spent on tasks or transactions in the database, between these 2 snapshots. | |__ o. For example, the normal working time is 8 hours daily basis. But, when you fullfil the spreadsheet, it is normal to put 3 hours on task A, 4 hours on task B, and 2 hours on C. | Because, sometimes, you were working on the tasks paralell, and finially, the sum of your total logical working hour is 9, higher than government regulated. | |__ o. Sometimes, we treat "DB Time" as a ruler to understand how busy the database was intuitively. <4> Host & Instance CPU: | |__ o. Host CPU indicates what is the Idle Time spanning 2 snapshots used by all the processes were running on the system. | |__ o. Instance CPU indicates how much percent was occupied by Oracle database assicated process. %Total CPU * %Busy CPU = how much CPU was consumed by Oracle instance. Reference: | |__ o. https://blog.csdn.net/u010719917/article/details/52955252
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