Oracle与Linux性能监控全攻略
1. Oracle性能监控
1.1 字典缓存（Dictionary Cache）
可以从V$ROWCACHE动态性能视图获取由语句固定字典缓存对象引起的全局排队活动的额外信息。该视图会报告GES锁请求、冲突和释放情况，示例查询如下：
SQL> li 1 SELECT 2 parameter AS "Cache Name", 3 dlm_requests AS "Requests", 4 dlm_conflicts AS "Conflicts", 5 dlm_releases AS "Releases" 6* FROM v$rowcache SQL> /查询结果示例：
| Cache Name | Requests | Conflicts | Releases |
| — | — | — | — |
| dc_rollback_segments | 99 | 0 | 0 |
| dc_free_extents | 0 | 0 | 0 |
| dc_used_extents | 0 | 0 | 0 |
| dc_segments | 7335 | 469 | 4158 |
| … | … | … | … |
应关注Conflicts列中的高值，例如上述示例中序列有43次冲突。未缓存的序列是RAC中最常见的性能问
