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Oracle EBS R12:1.3/ DB 12c- Buffer busy waits on undo segments

in SQL Performance (MOSC) 3 commentsAnswered

We are using Automatice Undo management. One of the user while running a program was waiting on buffer busy waits for more than 20 mins on the same file (p1) and blcoks(p2). It turned out that block belong to undo segment.

The user session was terminated as it created block chains, hence could not take system dump.

What actions are needed to find out why the session was waiting for undo segment? No errors reported in the alert log. I have checked awr reprots/ash reprots. I can see symptoms but not cause for the wait on rollback segment.

Any suggestions what can be done to find the rootcause?

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