Table Data Join across different hosts.

Question

I'm trying to create a table using data from three different tables on two different databases, two on one host, the third being on a different one. Is is possible?
Example:
Database: DB1
Table: Table1 t1
Host: Host1
User: dbuser1
Pass: dbpass1
Database: DB2
Table: Table2 t2
Host: Host2
User: dbuser2
Pass: dbpass2
Database: DB2
Table: Table2a t2a
Host: Host2
User: dbuser2
Pass: dbpass2
If all 3 tables were on the same host, I would write the query as:
select t1.column1,t2.column2,t2a.column3
from table1 t1,table2 t2,table2a t2a
where t1.column1=t2.column1
and t1.column2=t2.column2
and t1.column1=t2a.column1
and t2a.column2=t2.column2
I know it's going to a lot more difficult than the above. If someone could please help me, I'd greatly appreciate it.
Thank you,
Daniel

Answer 1

Just to make sure that you know that is almost as easy as you thought. It sounds like this is a one time thing, but please follow the recommendations of others as well:
Make sure you can connect to both DB1 and DB2 from host1.
From DB1
create database link DB2 connect to dbuser2 identified by dbpass2 using 'DB2';
select t1.column1,t2.column2,t2a.column3
from table1 t1,table2@DB2 t2,table2a@DB2 t2a
where t1.column1=t2.column1
and t1.column2=t2.column2
and t1.column1=t2a.column1
and t2a.column2=t2.column2;
Go and take a nap.
And the performance saving synonyms wink wink....
create synonym db2table2 for table2@DB2;
create synonym db2table2a for table2a@DB2;
Presents us with this query:
select t1.column1,t2.column2,t2a.column3
from table1 t1,db2table2 t2,tdb2table2a t2a
where t1.column1=t2.column1
and t1.column2=t2.column2
and t1.column1=t2a.column1
and t2a.column2=t2.column2;
As you can see all it really does is give you a layer abstraction, nothing performance wise.
-J