<?xml version="1.0" encoding="utf-8" ?><rss version="2.0"><channel><title><![CDATA[congwan1707的博客]]></title><description><![CDATA[]]></description><link>https://blog.youkuaiyun.com/congwan1707</link><language>zh-cn</language><generator>https://blog.youkuaiyun.com/</generator><copyright><![CDATA[Copyright &copy; congwan1707]]></copyright><item><title><![CDATA[innodb_autoinc_lock_mode]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373831</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373831</guid><author>congwan1707</author><pubDate>Mon, 26 Sep 2016 16:51:11 +0800</pubDate><description><![CDATA[innodb_autoinc_lock_mode 有三种值0 1 2 一般默认的为1
innodb_autoinc_lock_mode=0
这种为传统模式，所有的insert-like语句都会持有table-level A...]]></description><category></category></item><item><title><![CDATA[物理DG角色切换]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373826</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373826</guid><author>congwan1707</author><pubDate>Wed, 07 Sep 2016 00:07:17 +0800</pubDate><description><![CDATA[1.角色切换分为两种：


	一种是切换角色，一种是在主库故障的时候，切换至备库，这个时候如果不是在最大保护或者最大可用性的模式下，有可能会导致数据丢失。如果主库开启了闪回，那么主库还是有可能成为新的主库的备库的。...]]></description><category></category></item><item><title><![CDATA[物理DG 日志传输以及应用过程]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373832</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373832</guid><author>congwan1707</author><pubDate>Tue, 06 Sep 2016 23:20:10 +0800</pubDate><description><![CDATA[mysql 中的主备会经常碰到主库和备库日志传输延迟，其中一个role突然宕机，这时候会发生什么？


	最近刚好在生产环境中碰到切换物理DG的需求，参照学习，准备研究一下oracle中主备切换时日志未及时应用，or...]]></description><category></category></item><item><title><![CDATA[5.6的online ddl]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373830</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373830</guid><author>congwan1707</author><pubDate>Thu, 01 Sep 2016 14:55:49 +0800</pubDate><description><![CDATA[下午在更改一个表结构的时候，将其中的一个字段类型从varchar（30） 变更到varchar(512) 发现了上面tmp table的现象，而且造成很多元数据锁等待。不是说5.6支持online ddl 不需要creat...]]></description><category></category></item><item><title><![CDATA[ORACLE buffer cache 原理 --LRU链表（参照学习：oracle内核技术揭秘）]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373829</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373829</guid><author>congwan1707</author><pubDate>Wed, 31 Aug 2016 20:05:30 +0800</pubDate><description><![CDATA[OBJ-Q对象列表在合并IO的过程中起了很大作用，因为脏块在从CKPT-Q中移到对象列表的时候会将不同对象的块链在一起，这样更容易找到连续的块进行合并。


	


	LRU链表一共包括4个链表，主LRU、辅助...]]></description><category></category></item><item><title><![CDATA[ORACLE buffer cache 原理 --检查点队列链表（参照学习：oracle内核技术揭秘）]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373827</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373827</guid><author>congwan1707</author><pubDate>Tue, 30 Aug 2016 23:43:19 +0800</pubDate><description><![CDATA[CKPT-Q 和 LRU


	在update过程中，首先在前文所讲的CBC Latch的保护下修改数据，之后进程先持有 checkpoint queue latch，然后将5号文件中的1234号块加入到检查点队列（...]]></description><category></category></item><item><title><![CDATA[ORACLE buffer cache 原理 --hash链表（参照学习：oracle内核技术揭秘）]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373841</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373841</guid><author>congwan1707</author><pubDate>Tue, 30 Aug 2016 22:42:09 +0800</pubDate><description><![CDATA[对于一个块，磁盘中叫block,内存中叫buffer。如何知道一个块是否‘在buffer cache中呢？oracle 采用的是hash算法。根据文件号块号来计算hash值，根据该值 定位到想用的bucket


	...]]></description><category></category></item><item><title><![CDATA[mvcc-奇怪的现象]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373828</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373828</guid><author>congwan1707</author><pubDate>Tue, 30 Aug 2016 16:56:00 +0800</pubDate><description><![CDATA[奇怪的现象1：


	session1：


	root@localhost : test 08:43:09&gt; select * from test1;（1）
+---------+------+
|...]]></description><category></category></item><item><title><![CDATA[索引列选值会影响索引的选择么？]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373825</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373825</guid><author>congwan1707</author><pubDate>Tue, 30 Aug 2016 13:54:20 +0800</pubDate><description><![CDATA[试验之后得到的初步结论是：


	当org的值存在于t1表中的时候，走的是我们期望看到的idx4 当org的值不存在的时候看到的是...]]></description><category></category></item><item><title><![CDATA[oracle内存管理]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373822</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373822</guid><author>congwan1707</author><pubDate>Tue, 30 Aug 2016 10:24:59 +0800</pubDate><description><![CDATA[1&gt; 设定MEMORY_TARGET 和MEMORY_MAX_TARGET的值 可以指定自动管理内存方式，MEMORY_TARGET是可以动态调整的参数，则不是动态且有限制，所以不宜设置太高！ 


	...]]></description><category></category></item><item><title><![CDATA[元数据锁导致的会话等待]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373802</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373802</guid><author>congwan1707</author><pubDate>Fri, 26 Aug 2016 17:04:38 +0800</pubDate><description><![CDATA[在月底加分区的时候某个表发现一只卡在那，进入到对应实例发现大量的元数据锁等待


	


	


	这个问题的原因是：


	该系统之前的某个会话执行相关表的操作之后未提交会话，一直占据改表的元数据...]]></description><category></category></item><item><title><![CDATA[数据导入导出EXP/IMP]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373803</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373803</guid><author>congwan1707</author><pubDate>Tue, 23 Aug 2016 11:17:41 +0800</pubDate><description><![CDATA[1 将数据库TEST完全导出,用户名system 密码manager 导出到D:\daochu.dmp中 


	 exp system/manager@TEST file=d:\daochu.dmp fu...]]></description><category></category></item><item><title><![CDATA[安装oracle时内核参数的含义]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373790</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373790</guid><author>congwan1707</author><pubDate>Wed, 27 May 2015 08:40:55 +0800</pubDate><description><![CDATA[/*/etc/sysctl.conf*/ 


	kernel.shmall = 4294967296 --设置共享内存总页数。这个值太小有可能导致数据库启动报错。很多人调整系统内核参数的时候只关注SHMMAX...]]></description><category></category></item><item><title><![CDATA[数据导入SQLLDR]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373791</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373791</guid><author>congwan1707</author><pubDate>Thu, 21 May 2015 15:39:56 +0800</pubDate><description><![CDATA[create table test_lff 


	(id number, 


	name varchar2(10), 


	memo varchar2(10) 


	); 
...]]></description><category></category></item><item><title><![CDATA[游标的使用实例]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373798</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373798</guid><author>congwan1707</author><pubDate>Thu, 21 May 2015 14:16:30 +0800</pubDate><description><![CDATA[---带参数的循环游标的使用 


	DECLARE 


	 


	CURSOR mycursor(num varchar2) IS 


	 


	SELECT * FROM D...]]></description><category></category></item><item><title><![CDATA[数据库维护常用操作4--表空间操作]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373789</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373789</guid><author>congwan1707</author><pubDate>Thu, 21 May 2015 11:03:39 +0800</pubDate><description><![CDATA[select* from dba_data_files; 


	 


	1. 创建表空间: 


	SQL&gt; create tablespace lifenfang datafile '/...]]></description><category></category></item><item><title><![CDATA[数据库维护常用操作3--DDL语句查看]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373792</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373792</guid><author>congwan1707</author><pubDate>Thu, 21 May 2015 10:27:59 +0800</pubDate><description><![CDATA[2&gt;常用的查询函数相关定义的语句：  


	 


	select owner,object_name,object_type from dba_objects where object_name...]]></description><category></category></item><item><title><![CDATA[数据库维护常用操作命令2--约束]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373779</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373779</guid><author>congwan1707</author><pubDate>Thu, 21 May 2015 10:22:54 +0800</pubDate><description><![CDATA[---数据库开发基础---约束 


	1,约束的分类primary key（PK）主键约束, 


	foreign key(FK)外键约束, 


	unique(UK)唯一约束， ...]]></description><category></category></item><item><title><![CDATA[数据库维护常用操作命令1-表操作]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373775</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373775</guid><author>congwan1707</author><pubDate>Thu, 21 May 2015 10:21:35 +0800</pubDate><description><![CDATA[-- Create table （分区表） 


	create table T_ORD_ORDER 


	( 


	 order_id VARCHAR2(1...]]></description><category></category></item><item><title><![CDATA[日期函数以及常见的日期表达]]></title><link>https://blog.youkuaiyun.com/congwan1707/article/details/100373782</link><guid>https://blog.youkuaiyun.com/congwan1707/article/details/100373782</guid><author>congwan1707</author><pubDate>Wed, 20 May 2015 13:31:37 +0800</pubDate><description><![CDATA[alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';---设置日期显示格式 


	current_date 是客户端的时间，也就是当前会...]]></description><category></category></item></channel></rss>