12.2新特性之ADG多节点启动MRP进程

最新推荐文章于 2024-04-18 15:52:59 发布

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介绍了OracleDatabase12cRelease2(12.2.0.1)中新引入的多实例Redo应用特性，此特性仅适用于OracleRAC和RACOneNode数据库环境。新特性支持在多个实例上并行执行Redo应用，但不支持块变更跟踪和In-Memory列存储。当使用ALL选项时，Redo应用将在所有处于开放或挂载状态的实例上运行。

12.2新特性，ADG是RAC环境，在多个实例可以启动MRP进程recover，命令如ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION INSTANCES ALL

该特性只适用RAC和RAC one node环境数据库,不支持块跟踪,不支持In-Memeory列存储
注：MRP进程只在执行命令的节点运行，其他节点会产生pr* recovery processes进程。

D.1.1 Setting Up Multi-Instance Redo Apply

As of Oracle Database 12 c Release 2 (12.2.0.1), a new INSTANCES [ ALL | integer ] clause is available on the SQL ALTER DATABASE RECOVER MANAGED STANDBY DATABASE command.

It has the following restrictions:

The clause is applicable only for Oracle Real Application Clusters (Oracle RAC) or Oracle RAC One Node databases.
Block Change tracking is not supported.
In-Memory column store is not supported with multi-instance redo apply in an Active Data Guard (ADG) environment.

The ALL option causes redo apply to run on all instances in an Oracle RAC standby database that are in an open or mounted state at the time recovery is started. .All instances must be in the same state — either open or mounted. A mix of states is not allowed.

The integer option restricts the number of instances that redo apply uses to the number you specify. For integer, specify an integer value from 1 to the number of instances in the standby database. The database chooses the instances on which to perform Redo Apply; you cannot specify particular instances.

The V$RECOVERY_PROGRESS view is only populated on the instance where recovery was started (where the MRP0 process resides).

If you omit the INSTANCES clause, then recovery happens on only one instance where the command was issued.

Because recovery processes ship redo among instances, redo apply performance is directly related to network bandwidth and latency.

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