What is the difference between startup Upgrade and Migrate

What is the difference between startup Upgrade and Migrate:



startup migrate:
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Used to upgrade a database till 9i.


Startup Upgrade ?
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From 10G  we are using startup upgrade to upgrade database.


What happens internally when you use startup upgrade/migrate?
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It will adjust few database (init) parameters (irrespective of what you have defined) automatically to certain values in order to run upgrade scripts smoothely.

in other way..it will issue few alter statements to set certain parameters which are required to complete the upgrade scripts without any issues.