The DRIVING_SITE hint forces query execution to be done at a different site than that selected by Oracle. This hint can be used with either rule-based or cost-based optimization.

driving_site_hint::=

where table is the name or alias for the table at which site the execution should take place.

For example:

SELECT /*+DRIVING_SITE(departments)*/ * 
FROM employees, departments@rsite 
WHERE employees.department_id = departments.department_id;

If this query is executed without the hint, then rows from departments are sent to the local site, and the join is executed there. With the hint, the rows from employees are sent to the remote site, and the query is executed there, returning the result to the local site.

This hint is useful if you are using distributed query optimization.

在分布式应用中很有用，今天碰到dblink远程访问性能问题，使用这个hint,问题解决。记录一下，以备后用。