改变数据库

改变数据库 “更改数据库的行为

句法

ALTER DATABASE alter_database_command

Where alter_database_command can be one or more of the following:

CHANGE ENCRYPTION TYPE encryption_type

RUN GARBAGE COLLECTION target_size

Where encryption_type is one of the following:

NONE
AES128

Where target_size is the desired amount of used memory (in bytes).

描述

Use 改变数据库 to change the operation of the database.

The 改变数据库 command affects all SMs and TEs in the database.

修改存储加密类型

NOODB支持这些加密类型:

加密类型 描述

NONE

数据库中未启用存储加密

AES128

使用AES-128密码加密存储

The current storage encryption type of the database can be determined by querying the DISK_ENCRYPTION column in the SYSTEM.NODES table.

If the DISK_ENCRYPTION column contains a percent complete, the SM is in the process of changing the encryption type of its storage.

请求垃圾收集

The RUN GARBAGE COLLECTION command is used to request that each SM and TE in the database perform one round of flushing cached data from memory. This process will stop either when the target_size memory usage is reached, or when all unused data has been released. 此命令不会强制在要释放的数据库使用的内存。 最好允许每个进程执行自己的内存管理:用户在正常情况下不应需要此命令。

从内存中刷新缓存数据可以显着影响数据库的性能,直到重新填充缓存。 在特定情况下,Nuodb支持可以建议该命令。