Deleteing large number of rows_urgent

Question

Hi Friends,
I need to write a procedure which will purge a table having more than 8 crores records based on the parameter passed by the user.We have open a cursor and in loop we are deleting one by one and when the count reaches 50,000 we issue commit so the rollback segment problem can be avoided.But this is taking plenty of time...very very slow.Is there any other way through which we can improve the perfomance.Instead of deleting one by one is it possible to delete 20000 rows in a fetch.
Please suggest.

Answer 1

try BULK COLLECT method of pl/sql.
it has the option for you to process a set of records with a single execution.
here is an example.
declare
type ty_dept is table of number index by binary_integer;
dept_list ty_dept;
cursor cur_dept is select deptno from dept;
begin
open cur_dept;
loop
--do bulk collect 1000 at a time
fetch cur_dept bulk collect into dept_list limit 1000;
exit when cur_dept%notfound;
--process in bulk
forall i in 1..dept_list.count
delete from emp where deptno = dept_list(i);
end loop;
end;
in the above example it process 1000 at a time. so instead of looping 1000 times and execute delete statements 1000 times it does once.
maybe this should improve you performance.
bench mark with initial some set of records before applying for entire 8 crores.