Long running operations, v$session_longops

At the end of the last year there were a few questions about long running operations. I was inspired by these questions to write an article describing longops.
It can be found in http://www.gplivna.eu/papers/v$session_longops.htm

Main facts highlighted there are as follows (first two are probably commonly known, but 3) and 4) are usually targets of questions):

1. Not all operations that are running longer than 6 seconds are considered as long operations. Built-in long operation types are strongly defined although increasing with every new Oracle version.
2. There are some other criteria to show the particular operation type in v$session_longops.
3. Long operations of particular kind can be very different i.e. they can actually do many more things behind the scenes and one cannot find out that just looking at long operation.
4. Oracle considers long operations as linear operations (each unit of work takes the same amount of time) therefore estimated completion time can be inaccurate in case the real process is not linear.

Gints Plivna
http://www.gplivna.eu

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