Lock tables when load data

Question

Are there any way to lock tables when i insert data with SQL*Loader? or oracle do it for me automatically??
how can i do this?
Thanks a lot for your help

Answer 1

Are there any problem if in the middle of my load (and commits) an user update o query data ?The only problem that I see is that you may run short of undo space (rollback segment space) if your undo space is limited and the user is running a long SELECT query for example: but this problem would only trigger ORA-1555 for the SELECT query or (less likely since you have several COMMIT) ORA-16XX because load transaction would not find enough undo space.
Data is not visible to other sessions, unless, the session which is loading data, commits it. That's the way Oracle handle the read committed isolation level for transaction.
See http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96524/c21cnsis.htm#2689
Or what happens if when i want to insert data someone has busy the table?You will get blocked if you try to insert data that has the same primary key as a row being inserted by a concurrent transaction.