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 Originally Posted by pranavgovind
Tamilselvan,
I understand, it locks the child table record when we delete partent record(ON DELETE CASCADE). Why we need index on FK's? I am not really understand why we need index on FK's. Can you please explain.
Govind
Please read the post from the beginning.
Modic and I explained. Prior to 9i, Oracle would lock the child table for the duration of the transaction if there is NO FK index, so other transaction waits until the previous transaction commits/rollbacks. As Modic explained, 9i and 10g place shared lock on the child table but do not prevent other transactions to do DML on other rows on the child table.
Tamil
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