redo log在初始化时会开辟一段连续的内存空间,写入是顺序io,性能好。 实际上undo log并不是直接写入到磁盘,而是先写入到undo log buffer中,当redo log持久化时undo log就同时持久化到磁盘了 用undo log 和redo log只需要经过一次磁盘就可以了,undo log并不是直接写入到磁盘而是写入到redo log里面,所以经过一次i...
• 在commit之前,redo log buffer中已经产生了上面两项的redo • 根据lgwr将redo从redo log buffer写到磁盘的机制,比如工作时间,有可能将部分redo数据写入磁盘 • 已经获得了所需全部锁 • 在commit当时,为事务生成一个SCN • lgwr将剩余的redo写入磁盘,并且把SCN标记到current redo log file里。 • 到...
After digging around further, none of the solutions above work in the case of ctrl+z and ctrl+shift+z - this I believe is because regardless of if we manage to block the shortcut using a technique described above, the browser still preforms an undo/redo and jumps to the last input fiel...
Redo an action To redo something you've undone, press Ctrl+Y or F4. (If F4 doesn't seem to work, you may need to press the F-Lock key or Fn Key, then F4) on your keyboard, or select Redo on the Quick Access toolbar. (The Redo button only appears after you've undone...
Canvas图形编辑器-数据结构与History(undo/redo) 描述 对于编辑器而言,History也就是undo和redo是必不可少的能力,实现历史记录的方法通常有两种: 存储全量快照,也就是说我我们每进行一个操作,都需要将全量的数据通常也就是JSON格式的数据存到一个数组里,如果用户此时触发了redo就将全量的数据取出应用到Editor对象当中...
Undo & Redo Ever use the command line, hit the enter key and have that awful moment where you’re not sure if something dreadful just happened? How often do you or your coworkers find yourselves wishing you could undo something in Git? GitKraken Desktop can undo many of these changes ...
--对于Oracle来说,最具有革命性的新特性莫过于Oracle 6时出现的改变向量(changevector);改变向量:即描述数据块更改的信息, change vector 也是redo 和undo的核心。 This is thetechnology that keeps your data safe, minimizes conflict between readers andwriters, and allows for instance recovery, media recovery...
To undo or redo an operation, Choose Edit > Undo or choose Edit > Redo. To cancel an operation, hold down the Esc key until the operation in progress has stopped. Using the History panel while editingThe History panel (F10 or Window > History) lets you jump to any recent state of ...
达梦DM8之误删除undo/redo文件恢复测试 1测试说明 分以下两种情况: 1.1如果有备份文件 如果有备份文件,可以重新初始化一个新的数据库(初始化参数要和原库一样,比如页大小、大小写敏感、字符集等,这些可以在 DM 数据库安装路径,…/data/DAMENG 目录下以 dminit+日期时间.log 命名的文件中查询),然后将备份文件和...
I want to have a custom undo function that I can call using a button, which will undo the last change in a textbox after a keyup event. For instance, if I press down on A and put AAAA and then lift up, it will backup so that if I press B (resulting in AAAAB) and click ...