Compare 2 tables and insert rows missing in each table.

Question

I have a tough situation. I have two exact tables- one online and one offline database. I know that there are missing rows of data from each table, so I need to make a comparison of one table and insert rows that do not exist. I was thinking to try this, but it took over 3 hours to run and did not return anything:
insert into t
select * from t a
where not exists (select * from [email protected] b
where a.col1 != b.col1
and a.col2 != b.col2
and a.col3 != b.col3);
and it goes on for another 7columns.
The trouble I have is to include a date clause so that the query can be broken down into running only a few months of data comparisions at a time- the records go back 4 years to compare. Also is there a way to write this so that it will query both tables at the same time in order to speed things up- or is one table at a time the best advice? Each table has over 100 million records to compare, that's why I was hoping to use a date criteria since one column is date.
Let me know what you advise to make this work, I hope I was on the right track.

Answer 1

Not sure if the MINUS operator will perform better with your data set but;
SQL> create table t1 (some_id number, some_date date)
Table created.
SQL> create table t2 (some_id number, some_date date)
Table created.
SQL> insert into t1 values (1, trunc(sysdate))
1 row created.
SQL> insert into t1 values (2, trunc(sysdate-5))
1 row created.
SQL> insert into t1 values (4, trunc(sysdate-90))
1 row created.
SQL> insert into t2 values (1, trunc(sysdate))
1 row created.
SQL> insert into t2 values (3, trunc(sysdate-10))
1 row created.
SQL> insert into t2 values (5, trunc(sysdate-100))
1 row created.
SQL> select * from t1
   SOME_ID SOME_DAT
         1 07-07-30
         2 07-07-25
         4 07-05-01
3 rows selected.
SQL> select * from t2
   SOME_ID SOME_DAT
         1 07-07-30
         3 07-07-20
         5 07-04-21
3 rows selected.
SQL> insert into t1 (
   select some_id, some_date from t2 where some_date between sysdate-50 and sysdate
   minus
   select some_id, some_date from t1 where some_date between sysdate-50 and sysdate)
1 row created.
SQL> insert into t2 (
   select some_id, some_date from t1 where some_date between sysdate-50 and sysdate
   minus
   select some_id, some_date from t2 where some_date between sysdate-50 and sysdate)
1 row created.
SQL> select * from t1
   SOME_ID SOME_DAT
         1 07-07-30
         2 07-07-25
         4 07-05-01
         3 07-07-20
4 rows selected.
SQL> select * from t2
   SOME_ID SOME_DAT
         1 07-07-30
         3 07-07-20
         5 07-04-21
         2 07-07-25
4 rows selected.