本文通过模拟误删用户默认表空间MAIN，并通过备份进行恢复的操作实验

1. 对数据库进行完全备份：
   1.1. 创建归档和完整备份目录
   mkdir /dm8/backup
   mkdir /dm8/arch

   1.2. 启用归档并指定归档目录
   alter database archivelog;
   alter database add archivelog ‘DEST=/dm8/arch, TYPE=LOCAL, FILE_SIZE=64, SPACE_LIMIT=0, ARCH_FLUSH_BUF_SIZE=0’;

   1.3. 完整备份数据库
   backup database full to “DB_DM01_FULL_2024_06_25_11_58_45” backupset ‘/dm/backup’;

   1.4. 将联机日志文件写入归档redo日志
   ALTER DATABASE ARCHIVELOG CURRENT;
   ALTER SYSTEM ARCHIVE LOG CURRENT;
   ALTER SYSTEM SWITCH LOGFILE;

2. 模拟MAIN表空间数据文件被误删
   rm MAIN.DBF

   重启实例后MAIN表空间处于MOUNT状态
   

3. 通过备份恢复MAIN表空间
   3.1. 停止实例并校验备份集
   [dmdba@bin]$ ./DmServiceDMSVR01 stop
   [dmdba@bin]$./dmrman
   RMAN> check backupset ‘/dm/backup’
   RMAN> show backupset ‘/dm/backup’
   

   3.2. 还原表空间
   RMAN> restore database ‘/dm/data/DM01/dm.ini’ tablespac MAIN from backupset ‘/dm/backup’;

   3.3. 恢复表空间
   RMAN> recover database ‘/dm/data/DM01/dm.ini’ tablespace MAIN;

   3.4 启动实例，MAIN表空间恢复正常
   [dmdba@bin]$ ./DmServiceDMSVR01 start