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In Oracle AWR report i see mention of three terms i.e. DB time , Elapses Time , CPU time but i am not sure what does they actually mean

Say i have got the AWR report for 15 mins i.e 900 seconds. There are two cores. Statement1 took 20 seconds to actually parse sql, executing sql etc and 10 seconds is wait time for other transaction to complete.

I believe DB time will be 900 secs. What will be be CPU and Elapsed time based on above use case ?

emilly
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3 Answers3

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"CPU time" meaning that your statement was used CPU for N seconds "Elapsed Time" mean all time for your statement, because you can spent it for waiting your HDD or locks or something else. It's all should be in AWR report if you tracing with maximum level

Leo
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Elapsed Time - When looking into AWR report, the Elapsed Time is the wall clock time of duration for which AWR report has been generated. For example, if we generate AWR report for 1 hour then Elapsed Time in AWR report will be 60 mins.

DB CPU - DB CPU is the CPU consumption by all Oracle server processes/foreground processes during snapshot interval time.

DB Time - DB time is a statistic which represents CPU time consumed by all Oracle processes over a period of time plus non-idle wait time. DB Time is the time spent by the database server executing user calls. DB Time is the total time spent by the all user processes which are actively working or actively waiting in the database calls. It includes the CPU Time, IO Wait time and non-idle time. It tells us that how much activity performed by the database for the duration.

Satya
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CPU is time spent on CPU. DB Time is time spent by foreground sessions actively waiting or actively working.

Consider you have a 10 minute AWR interval and system has 4 CPUs. The maximum CPU time available in that 10 minute period is 40 minutes.

also say that in that 10 minute period you have 3 sessions which have no idle time and are working or waiting for 100% of that 10 minute period.

The DB Time would be 30 minutes. (10*3) as all session either working or waiting during that 10 min

If you had four sessions actively working or actively waiting 100% of the time in that 10 minute period, then your DB time would be 40 minutes.

If you massively ramp up your activity and there were 100 session working/waiting for 10 minute period, DB time would be 1000 minutes.(10*100)

TejasT
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