Re: Tuning for rollbacks?

In Oracle, commit means: write a commit marker. Rollback means: read the associated rollback segments and update the corresponding database blocks.
This should explain why a rollback is 'slower' and why your method is very strange.
And no: you can't 'tune' rollback, apart from tuning your rollback segments, as rollback ought to be very rare, and not by design.

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Sybrand Bakker
Senior Oracle DBA