select /*+ driving_site(a) driving_site(b) driving_site(c) */ a.object_id,b.object_type,c.object_sid from a1@dblink1 a,a2@dblink2 b,a3@dblink3 c,d4 where a.object_id=b.object_id and b.object_ccid=c.object_ccid and c.object_sod=d.object_sod
加了 ‘/*+ driving_site(关联表1别名) driving_site(关联表2别名) driving_site(关联表3别名) */‘ 速度快甚至几十倍
原文：http://www.cnblogs.com/jamsbwo/p/5714665.html