ORA-14402: updating partition key column would cause a partition change

All,

I am updating the table based on the leading partition key and i got the error message.

ORA-14402: updating partition key column would cause a partition change

Again i changed the table as below.

alter table inventory ENABLE ROW MOVEMENT;

Now it works fine. I have two questions.

1. When we update the partition key, does oracle really move the data to different partition or it deletes the record in current partition and insert into another partition?.

2. Is it overhead when we update parition key? Any extra cost?

1. They are the same ... move = delete + insert

2. Yes ... you're not just updating a single column and leaving the row in place, you're actually moving the row to a new block. You're also requiring that two partitions of every local index be modified

Thank you for the answer.