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ORACLE DG之备库角色

原创 Oracle 作者:zr2095 时间:2015-09-26 23:17:12 0 删除 编辑
The types of standby databases are as follows:
  • hysical standby database //物理备库 ----只读

    Provides a physically identical copy of the primary database, with on disk database structures that are identical to the primary database on a block-for-block basis. The database schema, including indexes, are the same. A physical standby database is kept synchronized with the primary database, through Redo Apply, which recovers the redo data received from the primary database and applies the redo to the physical standby database.

    As of Oracle Database 11g release 1 (11.1), a physical standby database can receive and apply redo while it is open for read-only access. A physical standby database can therefore be used concurrently for data protection and reporting.

    提供了一个物理上相同的主数据库的副本,与磁盘上数据库结构与主数据库block-for-block基础上。数据库模式,包括索引,是相同的。物理备用数据库与主数据库保持同步,通过重做,重做数据恢复了从主数据库和应用物理备用数据库的重做。
    Oracle数据库11g的版本1(11.1),物理备用数据库可以接收和重做时它是开放申请只读访问物理备用数据库因此可以同时用于数据保护和报告。


  • Logical standby database //逻辑备库------可sql查询和查看统计报告、升级数据库和补丁集

    Contains the same logical information as the production database, although the physical organization and structure of the data can be different. The logical standby database is kept synchronized with the primary database through SQL Apply, which transforms the data in the redo received from the primary database into SQL statements and then executes the SQL statements on the standby database.

    A logical standby database can be used for other business purposes in addition to disaster recovery requirements. This allows users to access a logical standby database for queries and reporting purposes at any time. Also, using a logical standby database, you can upgrade Oracle Database software and patch sets with almost no downtime. Thus, a logical standby database can be used concurrently for data protection, reporting, and database upgrades.

    包含相同的逻辑信息生产数据库,尽管数据的物理组织和结构可以是不同的。逻辑备用数据库与主数据库通过SQL应用保持同步,从而使数据重做了从主数据库为SQL语句然后在备用数据库上执行SQL语句。
    一个逻辑备用数据库可用于其他商业用途除了灾难恢复需求。允许用户访问一个逻辑备用数据库来进行查询和报告此外,使用一个逻辑备用数据库,您可以升级Oracle数据库软件和补丁集几乎没有停机时间。因此,可以使用一个逻辑备用数据库并发数据保护,报告和数据库升级。

  • Snapshot Standby Database //快照备库----read write完全可更新备用数据库

  • A snapshot standby database is a fully updatable standby database.

    Like a physical or logical standby database, a snapshot standby database receives and archives redo data from a primary database. Unlike a physical or logical standby database, a snapshot standby database does not apply the redo data that it receives. The redo data received by a snapshot standby database is not applied until the snapshot standby is converted back into a physical standby database, after first discarding any local updates made to the snapshot standby database.

    A snapshot standby database is best used in scenarios that require a temporary, updatable snapshot of a physical standby database. Note that because redo data received by a snapshot standby database is not applied until it is converted back into a physical standby, the time needed to recover from a primary database failure is directly proportional to the amount of redo data that needs to be applied.

    备用数据库快照是一个完全可更新备用数据库。
    就像一个物理或逻辑备用数据库,备用数据库快照从主数据库和档案接收重做数据。不像物理或逻辑备用数据库,备用数据库快照不适用它收到的重做数据。不想对快照备份数据库进行本地更新(指dml)后,直到重做数据接收到一个备用数据库快照被应用后,快照备库才转换为物理备用数据库,
    备用数据库快照最好需要一个临时的场景中使用,可更新快照的一个物理备用数据库。注意,因为重做数据接收到一个备用数据库快照不是应用,直到它被转换回一个物理备用,从主数据库故障恢复所需的时间成正比的重做数据量,需要应用。

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