OCP认证052考题解析：1Z0-V8.02-第79题
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79. You are working on a database that must be functioning 24 hours a day, 7 days a week. The database is configured in ARCHIVELOG mode.
Which two options do you have for performing user-managed backups? (Choose two.)
A.You can perform consistent backups only.
B.You can perform a complete database backup without shutting down the database instance.
C.You can back up data files only when all data files have the same SCN recorded in the control file.
D.You can back up only those data files whose headers are frozen by using ALTER TABLESPACE BEGIN BACKUP or ALTER DATABASE BEGIN BACKUP commands.
Answer: BD
一致性备份(冷备份)：在数据库正常关闭情况下做备份，数据库处于一致性状态。
(可以用于归档和非归档)，所有SCN号一致。缺点：数据库需要关闭。
非一致性备份(热备份)：数据库在open状态下备份(用于归档模式)，使用alter database/tablespace xxx begin backup开始备份。
优点：数据库不需要关闭，用于7x24事务处理的数据库。
