ORACLE parent latch和children latch
About parent vs child latches. There is no fundamental low level difference between parent and child latches, they are all small regions of memory modified with atomic test-and-set style opcodes.
You see parent (and solitary) latches from x$ksllt where kslltcnm = 0 and child latches have Kslltcnm > 0 (their child number is stored there).
V$LATCH_PARENT shows all latches with kslltcnm 0, V$LATCH_CHILDREN shows all latches with cnm > 0. V$LATCH just summarizes & groups all statistics up using the latch number, it doesn't care about parent vs child latches.
It's up to Oracle, how it uses the child and parent latches, normally when child latches are used, parent latches don't get used much (or at all), since all resources to be protected have been spread between child latches already.
今天看到书中讲LATCH的时候提到了两个视图V$LATCH_CHILDREN和V$LATCH_PARENT ，不太清楚两者的区别，去百度了一下，还没百度到，GOOGLE了才找到一篇相关的文章。
看了上面的讲解，我个人理解就是二者其实没什么区别，完全取决于ORACLE如何使用。
相关文档：
虽然学习Java很久了，自己也连接过一些数据库，比如mysql之类的，如今呢，也学习了一段时间的Oracle，然而呢，今天是我第一次连接Oracle，嘿嘿，应该还不算太迟吧。
今天呢，有点笨拙，大家莫笑！
我这是一个查询例子
首先，� ......
问题描述
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在试图启动数据库的时候,Oracle报告下列错误：
ERROR:
ORA-27101 Shared memory realm does not exist
ORA-01034 ORACLE not available
基本解释
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Error: ORA-27101
Text: shared memory realm does not exist
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Ca ......
1.使用产品：arcsde 9.3+oracle 10.2.0.1
2.问题描述：用arcmap访问空间数据，操作几分钟，arcmap无反应，数据库服务器端cpu占有率100%，gsrvr.exe进程数10+。
3.解决办法：升级oracle版本从10.2.0.1升级到10.2.0.3或者.2.0.4。
4.原因：据esri工程师所称，oracle10.2.0.1版本存在与arcgis不兼容的无法调节的bug。目前升 ......
SQL> SQLPLUS / AS SYSDBA
SQL> exec dbms_workload_repository.create_snapshot
SQL> exec:snap_id:=dbms_workload_repository.create_snapshot
SQL> var snap_id number
SQL> print snap_id
SQL> @?/rdbms/admin/awrrpt.sql
OracleAWR速查
1.查看当前的AWR保存策略
select * fro ......
今天在对表创建视图的时候，用户提示 ORA-01031用户权限不足
使用system用户对其分配dba等权限，依然无法创建视图。
继续赋予权限
grant select any table to AAA;
授予用户询所有表的权限
grant select any dictionary to AAA;
再次授取用户select任何字典的权限
......
