_optimizer_undo_changes

In short, what does the hidden parameter: _optimizer_undo_changes do? We are about ready to set this parameter to TRUE in our ERP database as per the request of Oracle but don't know if we will see any performance issues with this change.

Also, how do we find out the value of a hidden variable? For normal parameters, we look at v$parameter. I know that if you want to get a listing of all hidden parameters you can query X$KSPPI:

SELECT KSPPINM
FROM X$KSPPI
WHERE SUBSTR (KSPPINM, 1, 1) = '_'; How do I find out what the current value of _optimizer_undo_changes is set to? (TRUE || FALSE)?

Any pointers would be greatly appreciated! -- jeff

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| Jeffrey M. Hunter              |  WORK: jhunter_at_fore.com |


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