[오라클] "DRIVING_SITE" optimizer hint

DRIVING_SITE 힌트는 로컬 테이블과 원격 테이블 조인시 힌트로 주어진 테이블를 먼저
드라이빙 테이블로 선정한 후 처리하는 방식임. 힌트를 주지 않으면 보통 로컬 테이블이
드라이빙 테이블이 됨.

SELECT /*+DRIVING_SITE(dept)*/ *
FROM emp, dept@rsite
WHERE emp.deptno = dept.deptno;

If this query is executed without the hint, then rows from dept are sent to the local site, and the join is executed there. With the hint, the rows from emp 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.