Commit delete

Question

Hello,
I'm trying something new on this and I am wondering if anyone has ideas. In the past rollback segment size wasn't something that mattered. We could make them as big as we wanted. We can no longer do that so when I go to delete 4 million records from a table (can't use truncate because I'm using a where clause) I get "unable to extend rollback...." error. So I wrote this script that I thought would delete 10 records and then quit. (I would change it later to something larger.) Instead it gives the rollback error again. I've looked at other posts on this board but they seem a little complicated. Any ideas why this won't work?
set time on
set echo on
declare
cnt number(7) := 0;
tot number(7) := 0;
cursor C1 is select a.row_id from activity a
where a.row_id in (select b.row_id from activity2 b);
begin
for row_id in C1 loop
Delete from activity a where a.row_id in (select b.row_id from activity2 b);
tot := tot + 1;
cnt := cnt + 1;
if (cnt >= 10) then
          commit;
          close c1;
cnt := 0;
end if;
end loop;
commit;
dbms_output.put_line('activity records deleted: '||tot);
end;
/

Answer 1

Andrew:
Which sketch?
I have no real metrics for this, but I use this approach fairly regularly when refreshing a test environment from our production data to get rid of uneeded history. For a several million row table, the threshold appears to be deleting 40% or more of the table. I suspect that as table size increases, the threshold will decrease somewhat. One of these days, I will do some metrics.
Finding space is realtively easy, unless you are seriously constrained at the filesystem level. What I usually do if there is no space in an existing tablespace is create a new tablespace to hold the temporary data, then drop it when finished. This beats expanding rollback to accomodate the delete, since the space is not permanently allocated.
Also, you can usually enable constraints with NOVALIDATE, since the data was good originally. In John's case, I suspect that there are no foreign keys since he is deleting such a large percentage of the table.
TTFN
John