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  • MySQL VS SQL Server TCO and Annual Support & Maintenance Cost

    Reduced Database TCO by 90% compared to Microsoft SQL Server   Annual Support & Maintenance Cost Comparison  

  • MySQL Server Architecture

    MySQL 服务器架构：  

  • Oracle为何会发生归档日志archivelog大小远小于联机重做日志online redo log size的情况？

    《rac不到redo大小就切换是什么原因？》   这个帖子详细讨论了RAC或单机环境中归档日志没到online redolog size 大小就马上切换问题的成因， 主要是由于oracle内部算法所决定的，  一般不会造成实例 性能或可用性问题， 唯一的困扰可能是 生成了较多的小归档日志。  

  • Know more about RBA redo block address

    A “Redo Block Address” (RBA) describes a physical location within a redo log file. An RBA consists of the following: Log sequence number Block number within log file Byte offset within block The structure of the redo block address is given below : 1 – The number of the redo log. [4 bytes] 2 –…

  • DUL Unloading a truncated table with incomplete backup

    DUL Unloading a truncated table Situation A table was truncated, need to recover the data. The tablespace has three files, one datafile is missing from the backup and cannot be restored. DUL Background DUL can unload in several ways. It needs to know which blocks to read for a table. The default behaviour is to…

  • ORACLE DUL BLOCK INDEX

    The Block Index feature, support for corrupted file systems and disk groups You can even unload a database that has no data files anymore. A block index is a way to unload from any corrupted file system or disk. It will work for asm disk groups, but also for unix file systems. The idea is…

  • ORACLE DUL and ASM

    amdu Always good to know that starting from 11g amdu is included in the distribution. Amdu is the asm dump utility. Apart from dumping asm metadata it also has an -extract option to extract a file from an asm disk group. It is a standalone utility, if needed you can even use it with 10g.…

  • MySQL无处不在

    Mysql无处不在，Mysql  is everywhere。   支持绝大多数的主流操作系统 ， 包括:windows、MAC OS、Linux、solaris等。 支持大量的开发程序语言，包括: php、perl、python、ruby、java、C、C++、C# 等。    

  • LAMP Stack

    LAMP STACK  

  • 9i中DG remote archive可能导致Primary Database挂起

    9i中若dg的remove archive stuck卡住可能即便在Max Performance最大性能模式下也会导致Primary database 主库的local archive 本地归档无法正常进行， 进而导致Primary db hang挂起。 Solaris sparce 64  平台上的9.2.0.5 库 的相关日志：   Verifying the issue in the alert log Fri Oct 28 08:10:12 2011 ALTER SYSTEM SET log_archive_dest_1=’location=/u24/app/oradata/temp_arch’ SCOPE=BOTH; Fri Oct 28 08:10:51 2011 ORACLE Instance maclean – Can not allocate log, archival required Fri Oct 28 08:10:51 2011…