Wednesday Sep 19, 2012

Parameter _rollback_segment_count can cause trouble

Just some weeks ago we've learned that setting the hidden underscore parameter:

_rollback_segment_count

may cause trouble during upgrade. This parameter is used in very rare cases to have under all circumstances and situations this specified number of UNDO's online. Now during upgrade this may result in massive latch contention due to bug14226559 - and there's a patch available as well. Recommendation is to unset it during upgrade.

I don't think that many people will hit this as I personally haven't seen databases with this underscore in their init.ora or spfiles. So take this post more or less as a reminder for myself :-)

About

Mike Dietrich - Oracle Mike Dietrich
Master Product Manager - Database Upgrade & Migrations - Oracle

Based in Germany. Interlink between customers/partners and the Upgrade Development. Running workshops between Arctic and Antartica. Assisting customers in their reference projects onsite and remotely. Connect via:

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