undo

ipv6 neighbor ipv6-address mac-addressipv6 //使能设备转发IPv6单播报文，包括本地IPv6报文的发送与接收。 ipv6 address anycast //用来配置IPv6任播地址。 ipv6 address auto global //使能无状态自动生成IPv6全局地址功能。 ipv6 address auto link-local //配置自动生成的链路本地地址。 ipv6 address link-local //配置接口的链路本地地址 ipv6 address eui- 64 //配置接口的EUI-64格式的全球单播地址 ipv6 enable //接口上使能IPv6功能。 ipv6 icmp blackhole unreachable send //使能在匹配IPv6黑洞路由后回应ICMP目的不可达报文的功能。 ipv6 icmp redirect send //使能系统发送ICMPv6重定向报文功能。 ipv6 icmp port-unreachable send //使能接口的ICMPv6端口不可达报文的发送功能。 ipv6 icmp hop-limit-exceeded send //使能接口的ICMPv6跳数超大报文的发送功能。 ipv6 icmp receive //使能系统接收ICMPv6报文功能。 //缺省情况下

66、Examine these SQL statements and their output: A. Inactive undo will never be retained for more than 15 minutes. B. The undo tablespace can grow automatically if there is not enough space to retain active undo. C. Inactive undo will be retained as long as possible within the limits of the current size of the undo tablespace. D. Inactive undo will always be retained for at least 15 minutes. E. Active undo will be retained as long as needed by transactions. Correct Answer: BE 北京CUUG整理，转载请注明，OCP讨论群：569933648/836361015

1.Redo Log The redo log is a disk-based data structure used during crash recovery to correct data written by incomplete transactions. During normal operations, the redo log encodes requests to change table data that result from SQL statements or low-level API calls. Modifications that did not finish updating the data files before an unexpected shutdown are replayed automatically during initialization, and before the connections are accepted. ib_logfile0 ib_logfile1 1.1 Changing the Number or Size of Redo Log Files Stop the MySQL server and make sure that it shuts down without errors. my.cnf

11G Undo使用率很高问题 http://blog.itpub.net/12679300/viewspace-1164916/ 原创 Oracle 作者： wzq609 时间：2014-05-20 10:23:29 2623 0 事件背景： 公司的ERP数据库是11.2.0.3的版本，最近观察到一个奇怪的现象就是数据库的UNDO表空间的使用率一直居高不下；UNDO表空间的大小为76G，但是使用率一直保持着70%以上。 趁此机会又重新学习了一遍Undo的知识，最终解决了这个问题，以下是解决过程中整理的文档。（以下都是从Oracle联机文档里面找到的） 一、What Is Undo?Oracle Database creates and manages information that is used to roll back, or undo, changes to the database. Such information consists of records of the actions of transactions, primarily before they are committed. These records are collectively referred to as undo.Undo records are used to:Roll back

2 参数文件 2.1 参数文件的获取 oracle的初始化参数可以通过查询v$parameter视图得到，在SQL*PLUS中，可以用过show parameter命令来显示某些参数的设置值。 2.2 参数文件 初始化参数文件：pfile 服务器参数文件：spfile 视图v$spparamter记录spfile参数的设置。 没啥好说的，直接学习一下案例分析。 2.3 诊断案例 问题描述：数据库在重新启动时无法正常启动，检查发现undo表空间丢失。 2.3.1 检查alert日志文件 警报日志文件由按时间排序的消息和错误的记录组成。下列信息会记录在警报日志文件中： （1）内部错误和块损坏 （2）影响数据库结构和参数的操作 （3）例程启动时所有非缺省的初始化参数值 控制警报日志文件位置的初始化参数为：background_dump_dest，缺省文件名为alertorcl.log 查看oracle错误含义：oerr ora 30012（今天才发现oracle错误可以这么查，授人以鱼不如授人以渔啊） 检查警报日志，发现报错原因ora-30012：undo表空间不存在。 2.3.2 尝试重新启动 数据库，检查问题是否仍然存在 startup 启动失败，问题仍然存在 2.3.3 检查数据文件，看undo表空间是否存在 ls -ltr undotbs.dbf 文件存在 2.3.4

In Vim, I did too much undo. How do I undo this (that is, redo)? Ctrl + r Also check out :undolist , which offers multiple paths through the undo history. This is useful if you accidentally type something after undoing too much. Strange nobody mentioned :earlier / :later . To redo everything you just need to do later 9999999d (assuming that you first edited the file at most 9999999 days ago), or, if you remember the difference between current undo state and needed one, use Nh , Nm or Ns for hours, minutes and seconds respectively. + :later N<CR> <=> Ng+ and :later Nf for file writes. Vim

I'm currently working on an app that allows the user to draw pixelated images using OpenGL ES, but I don't know how to implement an undo function. How could I do it? I thought of using an image for every pixel and adding it to an array. Basically, how can I store the rectangles I use as pixels? charse you can try : NSData *data = [NSData dataWithBytes:vertexBuffer length:vertexCount * sizeof(GL_FLOAT) * 2] ; if (self.vertexBuffers == nil) self.vertexBuffers = [[NSMutableArray alloc] init]; [self.vertexBuffers addObject:data]; save every draw point to a array; if undo clear old buffer

I'm using the Vim 7.3 feature undofile the following way: if version >= 703 set undofile set undodir=$HOME/.vim/undo set undolevels=1000 set undoreload=10000 endif I am using the same .vimrc and the same files (within a cloud storage) on different machines which do not support Vim 7.3 but use the old 7.2 version which does not support undofile out of box. Is there a solution for the 7.2 version compatible with the 7.3 undofile? version check Because persistent undo was introduced with Vim 7.3, your version check is fine, and prevents errors in older Vims. Usually, you would check for the