摘要:
select for update 这种作用是在不产生任何修改的情况下对特定行产生行锁。 阅读全文
摘要:
1.进程信息 LMON:维护数据库集群层面的节点关系,并与其他实例的lmon定期进行心跳通信。 LMS:维护GRD中数据块资源的信息,完成数据块在实例之间的传递工作。 LMD:对排队资源进行管理。 LCK管理本地资源的实例锁管理。 DIAG负责转储数据库相关的诊断信息。 LMHB监控LMS、LMD、 阅读全文
摘要:
1.Overview of Data Blocks Oracle Database manages the logical storage space in the data files of a database in units called data blocks, also called O 阅读全文
摘要:
1.查看某个角色都有什么权限 2.查看数据库中默认角色有哪些 3.查看数据库中用户拥有的系统权限 4.查看用户拥有的角色 5.查看对象的授权者与获权者 未解决问题:imse1用户有imp/exp的角色,但是没有select any dictionary的权限,依然可以查看相应的数据字典。已经查询EX 阅读全文
摘要:
阅读全文
摘要:
测试语句 MERGE /*+ parallel(a 4) */ INTO dayu0322 aUSING dayu0404 bON (a.object_id=b.object_id) WHEN MATCHED THEN UPDATE set a.object_name='dayu'; MERGE I 阅读全文
摘要:
1.definition Direct path reads are generally used by Oracle when reading directly into PGA memory (as opposed to into the buffer cache). If asynchrono 阅读全文
摘要:
1.defination Waits for 'latch: cache buffers chains' indicate that a session is trying to find a database block in the buffer cache. To do this it has 阅读全文
摘要:
Database Buffer Cache Thedatabase buffer cache, also called the buffer cache, is the memory area that stores copies of data blocks read from data file 阅读全文
摘要:
The process of retrieve database buffer cache。 referer the book of advanced owi the vsdx file in https://pan.baidu.com/s/1pbUWESPL0FyqFDJhDkf2Lg passw 阅读全文