What happens to indexes while DML

what happens to index's while i execute the following statement
step 1 > delete from emp;
wht happens to index now ?
step 2 > insert into emp
select * from emp1;
wht happens to index now ?
step 3 > commit;
wht happens to index now ?
i only do insert on emp table , i got index's on two columns in it.
by disable / remove index before deleting the record and enabling the index after commit statement will my insert statement performance improve ?
thanks
Raj

infant_raj wrote:
what happens to index's while i execute the following statement
step 1 > delete from emp;
wht happens to index now ?Rows represented in the index are removed from it.
>
step 2 > insert into emp
select * from emp1;Rows might be added to the indexes if there is an indexable value in the new row.
>
wht happens to index now ?
step 3 > commit;
wht happens to index now ?Nothing
by disable / remove index before deleting the record and enabling the index after commit statement will my insert statement performance improve ?Probably not, when you take into account the overhead of dropping and recreating the index.
you should go to http://docs.oracle.com and look up the concepts Guide for your version.

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