你能想到这是一个种差异备份！
部分差异备份，基于部分备份。
需要执行完整备份后，才能执行差异备份。
A full database backup is required before a differential backup can be performed.
差异备份以上一次的增量备份或差异备份为基础。
Delta backups are based on the last incremental or delta backup.
这样，您可以通过为数不多的几个部分差异备份来补充部分备份。
This let you supplement a partial backup with a short series of differential partial backups.
对于差异备份，需要维护自上次完全备份以来采取的所有备份，以便能够重构数据。
For a delta backup, you need to maintain all the backups taken since the last full backup in order to be able to reconstruct the data.
最后，差异备份捕捉自上一次任何类型的备份以来的一切变化(有时也称2级备份)。
Finally, a delta backup captures anything that has changes since the last backup of any kind (sometimes called a level 2 backup).
对于大型数据库，进行差异备份的间隔可以比数据库备份更短，从而可降低丢失工作的可能性。
For large databases, differential backups can occur at shorter intervals than database backups, which reduces the work-loss exposure.
例如，为了将数据恢复到星期三工作结束时，需要星期一、星期二和星期三的差异备份镜像(或星期三的日志文件)。
For example, to recover data to the end of business day Wednesday, you would need the delta backup images for Monday, Tuesday, and Wednesday (or Wednesday's log files).
在处理像数据仓库环境中数据库那样的巨型数据库方面，Oracle和DB 2都提供了增量和差异备份，避免复制未更改的数据页。
Dealing with huge databases such as those in data warehouse environment, both Oracle and DB2 provide incremental and differential backup to avoid copying unchanged data pages.
下图阐述了差异增量备份的概念。
The diagram below illustrates the concept of differential incremental backup.
差异化备份——只对上次完全备份之后有过更改的页面进行备份。
Differential backup — Backs up all of the modified pages in a database after the last successful full backup is completed.
为了进行总体的对比，下面的表对比MySQL和DB 2Express - c在备份和恢复方面的差异。
For an overall comparisons, the following table show how they fare with one another in backup and restore space.
差异化部分备份——差异化部分备份仅记录自上一次部分备份以来文件组中发生更改的数据区。
Differential partial backup — This backup only records data that has changed in the filegroups since the preceding partial backup.
与完全数据库备份相比，差异数据库备份体积更小，速度也更快。
Differential database backups are smaller and faster than full database backups.
与完全数据库备份相比，差异数据库备份体积更小，速度也更快。
Differential database backups are smaller and faster than full database backups.
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