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I'm new to oracle and I have a problem because CPU Wait rises and I can't identify what is causing itenter image description here

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    It might be useful to indicate what query or tool is computing these values.
    – mustaccio
    Aug 15, 2022 at 21:28
  • I would hazard a guess it's Oracle Enterprise Manager. If so, there should be sections that give information at the host server level which might give an indication of what [else] the host was doing at the time.
    – Phill W.
    Aug 16, 2022 at 7:51

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"CPU Wait" is caused by Oracle processes having to wait to get CPU time from the operating system. This can be caused by several things, not all of which are internal to the database.

From How to reduce "CPU + Wait for CPU" or "CPU + CPU wait":

For your SQL statements experiencing high CPU utilization, look at the total number of executions and the average elapsed time per execution. If the average time is high, see if the SQL statement can be tuned to reduce the number read operations (logical and/or physical). If the number of executions is high, then look at the application code that is calling that SQL statement to see if there is a more efficient way of handling it. For example, performing the SQL iteratively in a loop can increase the total number of executions. Maybe we can rewrite the code to get the data in bulk instead of row by row.

From "Finding the Root Cause of CPU Waits Using Stack Profiling"

... the database is spending a lot of time somewhere, and this time is not accounted for by known database waits or time running on CPU. It could be an uninstrumented wait (the database process sleeping while e.g. waiting for some sort of resource occupied by a different process), or wait for the CPU time.

A scenario like this may require - as described in the article - troubleshooting at the user stack or OS kernel level to get to the bottom of things.

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