1  说明

对于shards之间具有Oracle Data Guard fast-start failover（数据库自动故障转移）的Oracle Data Guard物理复制的部署是自动的。 这是各个shards的默认Oracle高可用性（HA）配置。

优点：

1.  Automated deployment reduces administrative overhead.http://www.cndba.cn/Expect-le/article/2190

2.  Physical database replication provides the strongest data protection using real time Oracle data validation.

3.  Supports either asynchronous or synchronous replication for near-zero or zero data loss protection.http://www.cndba.cn/Expect-le/article/2190

4.  Automatic database failover provides high availability for server, database, network, and site outages.

5.  Read-only workloads may be load-balanced across all copies of shards used for HA for additional scalability when using Oracle Active Data Guard.

其他关于Sharding文章：

语句级别路由和Cross-Shard查询：http://www.cndba.cn/Expect-le/article/2166

Sharded和Duplicated表介绍：http://www.cndba.cn/Expect-le/article/2165http://www.cndba.cn/Expect-le/article/2190

搭建Oracle Sharded数据库：http://www.cndba.cn/Expect-le/article/2160

1.1   SDB使用Oracle Data Guard

1.1.1  System-Managed SDB使用DG

下图就是一个primary shardgroup Shardgroup1和两个standby shardgroup Shardgroup2和Shardgroup3.

Shardgroup1是有shards(1-3)组成，Shardgroup2是有shards(4-6)组成，Shardgroup3是有shards(7-9)组成。http://www.cndba.cn/Expect-le/article/2190

其中Shardgroup1和Shardgroup2是在同一个数据中心--同步复制，Shardgroup3是在异地数据中心--异步复制。

 

部署例子：

http://www.cndba.cn/Expect-le/article/2190

CREATE SHARDCATALOG –database host00:1521:shardcat –region dc1, dc2

ADD GSM -gsm gsm1 -listener 1571 –catalog host00:1521:shardcat –region dc1
ADD GSM -gsm gsm2 -listener 1571 –catalog host00:1521:shardcat –region dc2

ADD SHARDGROUP -shardgroup shardgroup1 -region dc1 -deploy_as primary
ADD SHARDGROUP -shardgroup shardgroup2 -region dc1 -deploy_as active_standby
ADD SHARDGROUP -shardgroup shardgroup3 -region dc2 -deploy_as active_standby

CREATE SHARD -shardgroup shardgroup1 -destination host01 -credential oracle_cred
CREATE SHARD -shardgroup shardgroup1 -destination host02 -credential oracle_cred
CREATE SHARD -shardgroup shardgroup1 -destination host03 -credential oracle_cred
...
CREATE SHARD -shardgroup shardgroup3  -destination host09 -credential oracle_cred

DEPLOY

1.1.2  Composite SDB使用DG

在复合分片中，SDB由多个shardgroup成。 但是，每个shardspace包含多个复制的shardgroup，而不是复制的分片。

 http://www.cndba.cn/Expect-le/article/2190

部署例子：

CREATE SHARDCATALOG -sharding composite –database host00:1521:cat –region dc1, dc2, dc3

ADD GSM -gsm gsm1 -listener 1571 –catalog host00:1521:cat –region dc1
ADD GSM -gsm gsm2 -listener 1571 –catalog host00:1521:cat –region dc2
ADD GSM -gsm gsm3 -listener 1571 –catalog host00:1521:cat –region dc3

ADD SHARDSPACE -shardspace shardspace_a
ADD SHARDSPACE -shardspace shardspace_b

ADD SHARDGROUP -shardgroup shardgroup_a1 –shardspace shardspace_a -region dc1 -deploy_as primary
ADD SHARDGROUP -shardgroup shardgroup_a2 –shardspace shardspace_a -region dc1 -deploy_as active_standby
ADD SHARDGROUP -shardgroup shardgroup_a3 –shardspace shardspace_a -region dc3 -deploy_as active_standby
ADD SHARDGROUP -shardgroup shardgroup_b1 –shardspace shardspace_b -region dc1 -deploy_as primary
ADD SHARDGROUP -shardgroup shardgroup_b2 –shardspace shardspace_b -region dc1 -deploy_as active_standby
ADD SHARDGROUP -shardgroup shardgroup_b3 –shardspace shardspace_b -region dc2 -deploy_as active_standby

CREATE SHARD -shardgroup shardgroup_a1 -destination host01 –credential orcl_cred  
...
CREATE SHARD -shardgroup shardgroup_b3 -destination host09 -credential orcl_cred

DEPLOY

http://www.cndba.cn/Expect-le/article/2190

更为相信信息，请查看官方文档：

http://docs.oracle.com/database/122/ADMIN/sharding-high-availability.htm#ADMIN-GUID-C668B8C7-0F94-4F85-B8E1-A6B91548BBB6

2  实验-System-Managed SDB使用DG

详细请参考：搭建Oracle Sharded数据库：http://www.cndba.cn/Expect-le/article/2160

多了一个步骤，其他操作均不变。

--在添加shardgroup时，不仅添加primary shardgroup，也要添加arctive_standby shardgroup

GDSCTL> add shardgroup -shardgroup primary_shardgroup -deploy_as primary -region region1

GDSCTL> add shardgroup -shardgroup standby_shardgroup -deploy_as active_standby -region region2

--添加shards节点主机时，指定primary shardgroup和active_standby shardgroup

GDSCTL> add invitednode sdb1
GDSCTL> create shard -shardgroup primary_shardgroup -destination sdb1 -credential credential_name -sys_password oracle

GDSCTL> add invitednode sdb2
GDSCTL> create shard -shardgroup standby_shardgroup -destination sdb2 -credential credential_name -sys_password oracle

GDSCTL> add invitednode sdb3
GDSCTL> create shard -shardgroup primary_shardgroup -destination sdb3 -credential credential_name -sys_password oracle

GDSCTL> add invitednode sdb4
GDSCTL> create shard -shardgroup standby_shardgroup -destination sdb4 -credential credential_name -sys_password oracle

那么sdb2是sdb1的物理备库，sdb4是sdb3的物理备库。

下面就直接DEPLOY即可，所有操作都由Oracle自动完成。

2.1   验证

GDSCTL> config shard
Name    Shard Group           Status    State        Region    Availability
----    -----------           ------    -----        ------    ------------
sh1      primary_shardgroup   Ok        Deployed     region1   ONLINE
sh2      standby_shardgroup   Ok        Deployed     region2   READ_ONLY
sh3      primary_shardgroup   Ok        Deployed     region1   ONLINE
sh4      standby_shardgroup   Ok        Deployed     region2   READ_ONLY

GDSCTL> databases
Database: "sh1" Registered: Y State: Ok ONS: N. Role: PRIMARY
Instances: 1 Region: region1
   Registered instances:
     cust_sdb%1

Database: "sh2" Registered: Y State: Ok ONS: N. Role: PH_STNDBY
Instances: 1 Region: region2
   Registered instances:
     cust_sdb%11

Database: "sh3" Registered: Y State: Ok ONS: N. Role: PRIMARY
Instances: 1 Region: region1
   Registered instances:
     cust_sdb%21

Database: "sh4" Registered: Y State: Ok ONS: N. Role: PH_STNDBY
Instances: 1 Region: region2
   Registered instances:
     cust_sdb%31

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Sharding Data Guard