Oracle数据库性能监控技巧,判断事务回滚段竞争的SQL查询语句:(当比率超过2时存在回滚段竞争,需增加更多回滚段) select rn.name, rs.GETS, rs.WAITS, (rs.WAITS / rs.GETS) * 100 ratio from v$rollstat rs, v$rollname rn where rs.USN = rn.usn