Why can't I truncate table?

I want to lock a table to prevent changes, do some read-only processing on rows in the table, then truncate the table, and commit, e.g.

1. lock table xyz in exclusive mode;
2. select ... from xyz;
3. truncate table xyz;
4. commit;

I find (Oracle 7.3.3.4) that if another user attempts to insert into xyz after step 1, but before step 3, the truncate fails with:

ORA-00054: resource busy and acquire with NOWAIT specified

The other user's insert then succeeds.

If I 'delete from xyz' instead of 'truncate xyz' it works as expected.

Why can't the process that locks the table in exclusive mode then do a truncate when another process is waiting to insert?

Thanks for your help.

Bill Received on Sun Mar 14 1999 - 10:49:27 CST