Hi Tom,
I have a problem following
I have 2 database at 2 different site and my job is transfer user a scheduler job at site B, pulling data from site A via dblink_b2a. about 14m records/day
when I execute single statement:

    insert /*+ append */ into table_b 
      from select * from table_b@dblink_b2a
     where condition >= v_start_time
       and condition <  v_end_time
    ;

=> duration time about 15-20 minutes

But when I put it in procedure and run scheduler job, it ran very slowly ~15 hours and not completed yet.
My sample procedure:

create or replace procedure transfer_Data 
as 
    v_start_time date := trunc(sysdate - 1);
    v_end_time   date := trunc(sysdate);
begin 
    insert /*+ append */ into table_b 
      from select * from table_b@dblink_b2a
     where condition >= v_start_time
       and condition <  v_end_time
    ;
end; 

Please tell me reasons and advises for this case
Hope your responding as soon as you can
Thank you and best regards!

insert /*+ append */ into table_b 
      from select * from table_b@dblink_b2a
     where condition >= v_start_time
       and condition <  v_end_time    ;