Execute multiple Oracle SQL statements simultaneously - oracle

Question

I have an Oracle database that has 20 very large tables, each with hundreds of partitions. I can compress a table but it takes over 2 hours. This would mean over 40 hours to complete all 20 tables. I would like to run the partition compression simultaneously (1 per table). Because the partitions are added daily I need a utility to generate the "alter table ..." syntax at the time of the run. So far, all I can think of is to create a SQL for each of the 20 tables and their partitions, then run them in 20 SQLPlus sessions.
Is there a better, more automated way to do this?

Answer 1

You could submit several jobs, which will - in turn - run your code simultaneously. Here's an example:
Test tables - I want to modify ID's datatype to VARCHAR2(10)
SQL> create table t1 (id varchar2(2));
Table created.
SQL> create table t2 (id varchar2(2));
Table created.
SQL> create table t3 (id varchar2(2));
Table created.
A procedure which will utilize EXECUTE IMMEDIATE and is called from DBMS_JOB (see below):
SQL> create or replace procedure p_exe (par_what in varchar2) is
2 begin
3 execute immediate par_what;
4 end;
5 /
Procedure created.
Create jobs which will run the ALTER TABLE simultaneously
SQL> declare
2 l_str varchar2(200);
3 l_job number;
4 begin
5 for cur_r in (select 't1' table_name from dual union all
6 select 't2' from dual union all
7 select 't3' from dual)
8 loop
9 l_str := 'alter table ' || cur_r.table_name || ' modify id varchar2(10)';
10 dbms_output.put_line(l_str);
11 dbms_job.submit(l_job,
12 'p_exe(' || chr(39) || l_str || chr(39) ||');',
13 sysdate
14 );
15 commit;
16 end loop;
17 end;
18 /
PL/SQL procedure successfully completed.
Jobs are now running; in a few moments (in my case, as it is a simple one - you'd check that somewhat later), check what's being done:
SQL> desc t1;
Name Null? Type
----------------------- -------- ----------------
ID VARCHAR2(10)
SQL> desc t3;
Name Null? Type
----------------------- -------- ----------------
ID VARCHAR2(10)
SQL> desc t3;
Name Null? Type
----------------------- -------- ----------------
ID VARCHAR2(10)
SQL>