6 Altering an Active Standby Pair

Making DDL changes in an active standby pair

You can perform the following tasks in an active standby pair without stopping the replication agent:

• Create, alter, or drop a user. These statements are replicated.

• Grant or revoke privileges from a user. These statements are replicated.

• Create or drop a view, a materialized view, a PL/SQL function, PL/SQL procedure, PL/SQL package, or PL/SQL package body. These objects are not replicated. See "Creating a new PL/SQL object in an existing active standby pair" for more information.

• Add a column to a replicated table or drop a column from a replicated table. The change is replicated to the table in the standby database.

• Create or drop a table, including global temporary tables. The CREATE TABLE and DROP TABLE statements can be replicated to the standby database. The new table can also be included in the active standby pair.

• Create or drop a synonym. The CREATE SYNONYM and DROP SYNONYM statements can be replicated to the standby database.

• Create or drop an index. The CREATE INDEX and DROP INDEX statements can be replicated to the standby database.

Use the DDLReplicationLevel and DDLReplicationAction connection attributes to control what happens when you want to perform these tasks.

DDLReplicationLevel can be set as follows:

• DDLReplicationLevel=1. CREATE or DROP statements for tables, indexes, or synonyms are not replicated to the standby database. However, you can add to or drop columns from a replicated table, and those actions will be replicated to the standby database.

• DDLReplicationLevel=2 is the default, which enables replication of creating and dropping of tables, indexes, and synonyms.

You can set the DDLReplicationLevel attribute by using the ALTER SESSION statement:

ALTER SESSION SET ddl_replication_level=1;

If you want to include a table in the active standby pair when the table is created, set the DDLReplicationAction connection attribute to 'INCLUDE'. If you do not want to include a table in the active standby pair when the table is created, set DDLReplicationAction='EXCLUDE'. The default is 'INCLUDE'.

You can set the DDLReplicationAction attribute by using the ALTER SESSION statement:

ALTER SESSION SET ddl_replication_action='EXCLUDE';

To add an existing table to an active standby pair, set DDLReplicationLevel=2 and use the ALTER ACTIVE STANDBY PAIR INCLUDE TABLE statement. The table must be empty.

When DDLCommitBehavior=0 (the default), DDL operations are automatically committed. When RETURN TWOSAFE has been specified, errors and timeouts may occur as described in "RETURN TWOSAFE". If a RETURN TWOSAFE timeout occurs, the DDL transaction is committed locally regardless of the LOCAL COMMIT ACTION that has been specified.

Command > ALTER SESSION SET ddl_replication_level=2;
Session altered.
Command > ALTER SESSION SET ddl_replication_action='INCLUDE';
Session altered.

Command > CREATE TABLE tabinclude (col1 NUMBER NOT NULL PRIMARY KEY);
Table created.

Command > INSERT INTO tabinclude VALUES (55);
1 row inserted.

Command > SELECT * FROM tabinclude;
< 55 >
1 row found.

Command> ALTER SESSION SET ddl_replication_level=2;
Session altered.
Command> ALTER SESSION SET ddl_replication_action='exclude';
Session altered.

Command> CREATE TABLE newtab (a NUMBER NOT NULL);
Command> ALTER ACTIVE STANDBY PAIR INCLUDE TABLE newtab;
 8000: No primary or unique index on non-nullable column found for replicated 
 table TERRY.NEWTAB
The command failed.

Command> CREATE UNIQUE INDEX ixnewtab ON newtab(a);
Command> ALTER ACTIVE STANDBY PAIR INCLUDE TABLE newtab;

Command> INSERT INTO newtab VALUES (5);
1 row inserted.

Command> SELECT * FROM newtab;
< 5 >
1 row found.

Command> ALTER SESSION SET ddl_replication_level=2;
Session altered.
Command> ALTER SESSION SET ddl_replication_action='include';
Session altered.

Command> CREATE TABLE tab2 (a NUMBER NOT NULL, b NUMBER NOT NULL, 
       > PRIMARY KEY (a));

Command> CREATE UNIQUE INDEX ixtab2 ON tab2 (b);

Command> indexes;
 
Indexes on table TERRY.TAB2:
  IXTAB2: unique T-tree index on columns:
    B
  TAB2: unique T-tree index on columns:
    A
  2 indexes found.
 
Indexes on table TERRY.NEWTAB:
  NEWTAB: unique T-tree index on columns:
    A
  1 index found.
 
Indexes on table TERRY.TABINCLUDE:
  TABINCLUDE: unique T-tree index on columns:
    A
  1 index found.
4 indexes found on 3 tables.

Command > ALTER SESSION SET ddl_replication_level=2;
Session altered.
Command > ALTER SESSION SET ddl_replication_action='INCLUDE';
Session altered.

Command> CREATE SYNONYM syntabinclude FOR tabinclude;
Synonym created.

Command> synonyms;
TERRY.SYNTABINCLUDE
1 synonym found.

Making other changes to an active standby pair

You must stop the replication agent to make these changes to an active standby pair:

• Include or exclude a sequence

• 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)

To alter an active standby pair according to the preceding list, complete the following tasks:

1. Stop the replication agent on the active database. See "Starting and stopping the replication agents".

2. If the active standby pair includes cache groups, stop the cache agent on the active database.

3. Use the ALTER ACTIVE STANDBY PAIR statement to make changes to the replication scheme. See "Examples: Altering an active standby pair".

4. Start the replication agent on the active database. See "Starting and stopping the replication agents".

5. If the active standby pair includes cache groups, start the cache agent on the active database.

6. Destroy the standby database and the subscribers.

7. Duplicate the active database to the standby database. You can use either the ttRepAdmin -duplicate utility or the ttRepDuplicateEx C function to duplicate a database. If the active standby pair includes cache groups, use the -keepCG command line option with ttRepAdmin to preserve the cache group. See "Duplicating a database".

8. Set up the replication agent policy on the standby database and start the replication agent. See "Starting and stopping the replication agents".

9. Wait for the standby database to enter the STANDBY state. Use the ttRepStateGet procedure to check the state.

10. If the active standby pair includes cache groups, start the cache agent for the standby database using the ttCacheStart procedure or the ttAdmin -cacheStart utility.

11. Duplicate all of the subscribers from the standby database. See "Duplicating a master database to a subscriber". If the active standby pair includes cache groups, use the -noKeepCG command line option with ttRepAdmin in order to convert the cache group to regular TimesTen tables on the subscribers. See "Duplicating a database".

12. Set up the replication agent policy on the subscribers and start the agent on each of the subscriber databases. See "Starting and stopping the replication agents".

ALTER ACTIVE STANDBY PAIR
  ADD SUBSCRIBER sub1;

ALTER ACTIVE STANDBY PAIR
  DROP SUBSCRIBER sub1
  DROP SUBSCRIBER sub2;

ALTER ACTIVE STANDBY PAIR
  ALTER STORE sub1 SET PORT 23000 TIMEOUT 180
  ALTER STORE sub2 SET PORT 23000 TIMEOUT 180;

ALTER ACTIVE STANDBY PAIR
  INCLUDE CACHE GROUP cg0;