unaccounted time in v$sql elapsed_time >> cpu_time + user_io_wait_time + concurrency_wait_time + etc

Regarding unaccounted time in v$sql, when elapsed_time is much bigger than cpu_time + user_io_wait_time + concurrency_wait_time + etc.

One reason: Log writer waits are not included into user_io_wait_time – it is truly a USER io time.

Test it: Stop log writer: kill -s SIGSTOP <lgwr_pid>. See how elapsed_time increases but other times stay unchanged.

Another credible reason: OS is losing time on paging (swapping)

 

 

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