发布时间：2013-03-06 10:41:21

oracle官网当一个用户发出select..for update的错作准备对返回的结果集进行修改时，如果结果集已经被另一个会话锁定，就是发生阻塞。需要等另一个会话结束之后才可继续执行。可以通过发出 select… for update nowait的语句来避免发生阻塞，如果资源已经被另一个会话锁定，则会返回以下错误：Ora-00054:resource busy and a.........【阅读全文】

发布时间：2013-02-26 12:58:02

通常,如果缓存的命中率太低可以增大缓存的大小和避免你的应用程序执行全表扫描.To increase cache size, first set the  DB_CACHE_ADVICE initialization parameter toON, and let the cache statistics stabilize. Examine the advisory data in theV$DB_CACHE_ADVICE view to determine the next increm.........【阅读全文】

发布时间：2013-02-25 09:52:57

However, increasing the cache size to 334MB would potentially decrease reads by a factor of .93 or 7%. If an additional 30MB memory is available on the host system and theSGA_MAX_SIZE setting allows the increment, it would be advisable to increase the default buffer cache pool size to 334MB.但是,.........【阅读全文】

发布时间：2013-02-22 10:53:12

7.2.2.1 Buffer Cache Advisory StatisticsA number of statistics can be used to examine buffer cache activity. These include the following:V$DB_CACHE_ADVICEBuffer cache hit ratiobuffer cache 报告的统计统计的数据能被用于检查buffer cache的活动。7.2.2.2 Using V$DB_CACHE_ADVICEThis view is .........【阅读全文】

发布时间：2013-02-21 09:51:13

设置db_cache_advice的初始参数, 动态调整buffer pool的大小To increase cache size, first set the DB_CACHE_ADVICE initialization parameter toON, and let the cache statistics stabilize. Examine the advisory data in theV$DB_CACHE_ADVICEview to determine the next increment required to significantly dec.........【阅读全文】