数据库大小MSSQL

Question

我有两个数据库：DB_1Large和DB_2Medium

• DB_1Large.mdb的大小为50 gb
• DB_2Medium.mdb的大小为16 gb

问题：

它看起来很荒谬，但这个数据库的备份有下一个尺寸：

• DB_1Large.bak - ~30 gb
• DB_2Medium - ~12 gb

在使用win rar或studio进行压缩之后，这会有下一个尺寸：

• DB_1Large.bak - ~2.5 gb
• DB_2Medium - ~5.5 gb

为什么以及如何缩小它？

两个数据库的exec sp_spaceused：

database_name   database_size   unallocated space   
DB_1Large   52349.38 MB 20197.74 MB 
reserved    data    index_size  unused
30546184 KB 16273760 KB 13500336 KB 772088 KB

database_name   database_size   unallocated space   
DB_2Medium  17144.19 MB 4672.13 MB  
reserved    data    index_size  unused
12457024 KB 10608232 KB 1809120 KB  39672 KB

Answer 1

此处COMPRESSION在备份时指定，它将压缩数据库并进行备份

Use master
Go
BACKUP DATABASE [DatabaseName] 
TO  DISK = N'C:\Program Files\Microsoft SQL Server\MSSQL11.MSSQLSERVER\MSSQL\Backup\DatabaseName_2017-08-07.bak' 
WITH  COPY_ONLY, NOFORMAT, NOINIT,  
NAME = N'SqlClass-Full Database Backup', 
SKIP, NOREWIND, NOUNLOAD, COMPRESSION,  STATS = 5
GO

Answer 2

假设您不使用 if msg.is_multipart(): for part in msg.walk(): base = "" if (part.is_attachment()): payload = part.get_payload() for elem in payload: base+=str(elem) withattachment = "yes" name = part.get_filename() base=base.replace("\n","") else: base = None if (msg.is_attachment()): withattachment = "yes" name = msg.get_filename() base =msg.get_payload() 选项，您的数据库会相应地拥有30Gb和12Gb的数据。备份仅备份数据而不备份空白区域。

如果你对win rar压缩比感兴趣，也许你最好搜索它的压缩算法，也许你的第二个备份由于重复的字节组合而更“可压缩”