Bulk insert using stored procedure or trigger

Question

Hi ,
I have to insert around 40,000 rows in a table querying other database using database link.
Please advice whether I do using stored procedure or trigger.
Thanks.

Answer 1

Here is a basic benchmark that illustrates the difference between maximising SQL, or doing it in PL/SQL instead.
Care needs to be taken with such a benchmark in order for physical I/O not to negatively impact a test, and then have no impact in the second test as that data read from disk now sits in the cache.
So I ran it a couple of times in order to "warm up" the cache. I also put the maximise-SQL test first in order to show that it is still faster, despite any physical I/O it may do (which will likely be faster logical I/O with the second test).
Run on Oracle XE 10.2.0.1.
SQL> drop table my_objects_copy purge;
Table dropped.
SQL> create table my_objects_copy as select * from all_objects;
Table created.
SQL>
SQL> set timing on
SQL> begin
2 delete from my_objects_copy;
3
4 insert into my_objects_copy
5 select * from all_objects;
6
7 commit;
8 end;
9 /
PL/SQL procedure successfully completed.
Elapsed: 00:00:01.11
SQL> set timing off
SQL>
SQL> drop table my_objects_copy purge;
Table dropped.
SQL> create table my_objects_copy as select * from all_objects;
Table created.
SQL>
SQL> set timing on
SQL> declare
2 cursor c is select * from all_objects;
3 objRow ALL_OBJECTS%ROWTYPE;
4 begin
5 delete from my_objects_copy;
6
7 open c;
8 loop
9 fetch c into objRow;
10 exit when c%NOTFOUND;
11
12 insert into my_objects_copy
13 values objRow;
14
15 end loop;
16 commit;
17 end;
18 /
PL/SQL procedure successfully completed.
Elapsed: 00:00:03.21
SQL>
The cursor-fetch-loop is almost 3 times slower. The more rows there are to process, the slower the cursor-fetch-loop will become, as it will create more and more context switching and copying data between the SQL and PL engines and back.