TimesTen 数据库复制学习：9. 更改Active Standby Pair

Posted 2020-07-31 dingdingfish

在Active Standby Pair中复制DDL语句

在以下的例子中，active master为cachedb2, standby master为cachedb1

在Active Standby Pair复制数据库对象

DDLReplicationLevel 连接属性可以控制复制对象的行为。
DDLReplicationLevel = 1：不复制表，索引和同义词的create 和 drop，只复制复制表的添加和删除列操作
DDLReplicationLevel = 2: 缺省，复制表，索引和同义词的create 和 drop；DDLReplicationAction 必须设置为INCLUDE(缺省)
DDLReplicationLevel = 3：除了2 的所有行为外，还复制视图，序列，ttCacheUidPwdSet，以及可以为一个表加一个非空的列

控制复制的行为

以下是DDLReplicationLevel = 2 的情形(缺省)

cachedb2> call ttconfiguration;
......
< DDLReplicationAction, INCLUDE >
< DDLReplicationLevel, 2 >

cachedb2> create table a1(a int, primary key(a));
cachedb1> select * from a1;
cachedb2> insert into a1 values(1);
cachedb1> select * from a1;
< 1 >
cachedb2> drop table a1;
cachedb1> select * from a1;
 2206: Table TTHR.A1 not found

cachedb2> create table a2(a int);
17061: When DDLReplicationAction=‘INCLUDE‘ tables must be created with a primary key or a unique constraint on non-nullable column(s)


cachedb2> ALTER SESSION SET ddl_replication_action=‘EXCLUDE‘; <- 只是不复制DML，DDL仍复制

Session altered.
cachedb2> call ttconfiguration(‘DDLReplicationAction‘);
< DDLReplicationAction, EXCLUDE >
cachedb2> create table a1(a int, primary key(a));
cachedb1> select * from a1;
cachedb2> insert into a1 values(1);
cachedb1> select * from a1;

cachedb2>  create table a2(a int);
cachedb1> select * from a2;

cachedb1> repschemes;

Replication Scheme Active Standby:

  Master Store: CACHEDB2 on TIMESTEN-HOL
  Master Store: CACHEDB1 on TIMESTEN-HOL


  Excluded Tables: <- 注意这里
    TTHR.A1
    TTHR.A2

  Excluded Cache Groups:
    None

  Excluded sequences:
    None

  Store: CACHEDB1 on TIMESTEN-HOL
    Port: (auto)
    Log Fail Threshold: (none)
    Retry Timeout: 120 seconds
    Compress Traffic: Disabled

  Store: CACHEDB2 on TIMESTEN-HOL
    Port: (auto)
    Log Fail Threshold: (none)
    Retry Timeout: 120 seconds
    Compress Traffic: Disabled

  Store: _ORACLE from TIMESTEN-HOL
    Port: (auto)
    Log Fail Threshold: (none)
    Retry Timeout: 120 seconds
    Compress Traffic: Disabled


cachedb2> ALTER ACTIVE STANDBY PAIR INCLUDE TABLE a1;
cachedb2> insert into a1 values(3);
cachedb1> select * from a1;
< 3 >

cachedb2> repschemes;

Replication Scheme Active Standby:

  Master Store: CACHEDB2 on TIMESTEN-HOL
  Master Store: CACHEDB1 on TIMESTEN-HOL


  Excluded Tables:
    TTHR.A2
  Included Tables: <- 注意这里
    TTHR.A1

  Excluded Cache Groups:
    None

  Excluded sequences:
    None

  Store: CACHEDB1 on TIMESTEN-HOL
    Port: (auto)
    Log Fail Threshold: (none)
    Retry Timeout: 120 seconds
    Compress Traffic: Disabled

  Store: CACHEDB2 on TIMESTEN-HOL
    Port: (auto)
    Log Fail Threshold: (none)
    Retry Timeout: 120 seconds
    Compress Traffic: Disabled

  Store: _ORACLE from TIMESTEN-HOL
    Port: (auto)
    Log Fail Threshold: (none)
    Retry Timeout: 120 seconds
    Compress Traffic: Disabled

cachedb2> create index idx on a1(a);
17063: CREATE INDEX can only refer to empty tables when DDLReplicationLevel > 1

先不复制一个表，后续又将其加入到复制计划中

cachedb2> drop table a2;
cachedb2> ALTER SESSION SET ddl_replication_action=‘exclude‘;

Session altered.

cachedb2> create table a2(a int not null);
cachedb1> select * from a2;
cachedb2> ALTER ACTIVE STANDBY PAIR INCLUDE TABLE a2;
 8000: No primary or unique index on non-nullable column found for replicated table TTHR.A2
cachedb2> CREATE UNIQUE INDEX ixnewtab ON a2(a);
cachedb2> ALTER ACTIVE STANDBY PAIR INCLUDE TABLE a2;

下面例子说明了，如果一个表最初不在复制计划中，然后又加入复制计划，此表必须为空

cachedb2> ALTER SESSION SET ddl_replication_action=‘exclude‘;

Session altered.

cachedb2> create table a2(a int, primary key(a));
cachedb2> insert into a2 values(1);
cachedb2> insert into a2 values(2);
cachedb2> ALTER ACTIVE STANDBY PAIR INCLUDE TABLE a2;
17059: Replicated INCLUDE TABLE failed for (TTHR.A2) because the table is not empty
cachedb2> delete from a2;
cachedb2> ALTER ACTIVE STANDBY PAIR INCLUDE TABLE a2;

可以自动复制的对象

以下的对象在DDLReplicationLevel = 2或3时可以自动复制
* Create, alter, or drop a user with the CREATE USER, ALTER USER, or DROP USER statements.
* Grant or revoke privileges from a user with the GRANT or REVOKE statements.
* Alter a table to add or drop a column with the ALTER TABLE … ADD COLUMN or ALTER TABLE … DROP COLUMN statements. These are the only ALTER TABLE clauses that are replicated. However, when DDLReplicationLevel=2, you cannot alter a table to add a NOT NULL column to a table that is part of a replication scheme with the ALTER TABLE … ADD COLUMN NOT NULL DEFAULT statement. You can execute this statement if DDLReplicationLevel=3.
* Create or drop a table, including global temporary tables with the CREATE TABLE or DROP TABLE statements. The new table is also included in the active standby pair.
* Create or drop a synonym with the CREATE SYNONYM or DROP SYNONYM statements.
* Create or drop an index with the CREATE INDEX or DROP INDEX statements.

以下的对象仅在 DDLReplicationLevel = 3时可以自动复制
* 视图
* 序列(sequence)
* ttCacheUidPwdSet 操作

以上的复制操作均不需要停止复制代理。

对于物化视图的操作，更改autorefresh mode，PL/SQL都不会复制
如果需要创建PL/SQL函数，需要在所有的数据库中执行create语句并赋权

只有在空表创建的索引才会被复制，如果需要复制索引，可以将DDLReplicationLevel设为1，然后在所有数据库上手工建立

对于active standby pair的其它更改操作

以下的操作必须先停止复制代理：
* Include or exclude a cache group.
* Add or drop a subscriber.
* Change values in the STORE clause.
* Change network operations (ADD ROUTE or DROP ROUTE clause).

以上操作的过程如下：
1. 在active上停rep agent
2. 如果ASP包含缓存组，在active上停cache agent
3. 使用ALTER ACTIVE STANDBY PAIR修改复制schema
4. 在active上启动rep agent
5. 如果ASP包含缓存组，在active上启动cache agent
6. destroy所有的standby和subscriber
7. 使用ttRepAdmin 克隆standby
8. 启动standby上的rep agent
9. 等待standby的状态自动变为STANDBY(ttRepStateGet )
10. 如果ASP包含缓存组，在standby上启动cache agent
11. 通过standby克隆subsc
12. 启动subscriber上的复制代理