Oracle Streams
OVERVIEW OF ORACLE STREAMS ARCHITECTURE AND PROCESSING
Oracle Streams enables the propagation and management of data, transactions, and events in
a data stream either within a database, or from one database to another. Oracle Streams
consists of three components: capture, propagation, and apply. Each of these components is
made up of several Operating System processes,
Capture Component
The capture component mines redo logs from a source database and captures changes. It
consists of multiple operating-system processes. A reader process reads the redo log and
divides the redo log into regions. The preparer processes scan the regions defined by the
reader in parallel and pre-filter changes found in the redo log based upon user-defined rules.
A builder process merges redo records from the preparers and passes the merged redo
records to the capture process. The capture process then formats each change into a Logical
Change Record (LCR) and enqueues to a queue if it satisfies the defined rules.
You can configure capture locally at a source database or remotely at a downstream
database. A local capture process runs at the source database and captures changes from the
local source database redo log. You can configure a downstream capture process for realtime capture in which redo data from source database is transmitted to the downstream
database and written to the standby redo log files, from which the capture process captures
changes.
A single capture process can send changes to multiple propagation and apply processes. You
can also configure multiple capture processes.
Propagation Component
The propagation component uses queues to transfer the LCRs from the source database to
the destination database.
Apply Component
The apply component receives the LCRs and applies the changes at the target database. The
reader process dequeue LCRs from a queue, assembles the changes into transactions,
calculates the transaction dependencies, and passes the transactions to the coordinator. The
coordinator process assigns transactions to available appliers, based on the transaction
dependencies and ordering. The applier process executes the changes at the target database.
You can configure multiple appliers to increase apply parallelism.
. Enable ARCHIVELOG MODE on both databases
Reference: http://dbataj.blogspot.com/2007/09/how-to-enable-archivelog-mode.html
2. Create Stream administrator User
Source Database: DB1
SQL> conn sys@DB1 as sysdba
Enter password:
Connected.
SQL> create user strmadmin identified by strmadmin;
User created.
SQL> grant connect, resource, dba to strmadmin;
Grant succeeded.
begin dbms_streams_auth.grant_admin_privilege
(grantee => 'strmadmin',
grant_privileges => true);
end;
/
PL/SQL procedure successfully completed.
SQL> grant select_catalog_role, select any dictionary to strmadmin;
Grant succeeded.
Target Database: DB2
SQL> conn sys@DB2 as sysdba
Enter password:
Connected.
SQL> create user strmadmin identified by strmadmin;
User created.
SQL> grant connect, resource, dba to strmadmin;
Grant succeeded.
SQL> begin dbms_streams_auth.grant_admin_privilege
(grantee => 'strmadmin',
grant_privileges => true);
end;
/
PL/SQL procedure successfully completed.
SQL> grant select_catalog_role, select any dictionary to strmadmin;
Grant succeeded.
3. Setup INIT parameters
Source Database: DB1
SQL> conn sys@DB1 as sysdba
Enter password:
Connected.
SQL> alter system set global_names=true;
System altered.
SQL> alter system set streams_pool_size = 100 m;
System altered.
Target Database: DB2
SQL> conn sys@DB2 as sysdba
Enter password:
Connected.
SQL> alter system set global_names=true;
System altered.
4. Create Database Link
Target Database: DB1
SQL> conn strmadmin/strmadmin@DB1
Connected.
SQL> create database link DB2
connect to strmadmin
identified by strmadmin
using 'DB2';
Database link created.
Source Database: DB2
SQL> conn strmadmin/strmadmin@DB2
Connected.
SQL> create database link DB1
connect to strmadmin
identified by strmadmin
using 'DB1';
Database link created.
5. Setup Source and Destination queues
Source Database: DB1
SQL> conn strmadmin/strmadmin@DB1
Connected.
SQL> EXEC DBMS_STREAMS_ADM.SET_UP_QUEUE();
PL/SQL procedure successfully completed.
Target Database: DB2
SQL> conn strmadmin/strmadmin@DB2
Connected.
SQL> EXEC DBMS_STREAMS_ADM.SET_UP_QUEUE();
PL/SQL procedure successfully completed.
6. Setup Schema for streams
Schema: SCOTT
Table: Taj
NOTE: Unlock scott schema because in 10g scott schema is locked by default
Source Database: DB1
SQL> conn sys/manager@DB1 as sysdba
Enter password:
Connected.
SQL> conn scott/tiger@DB1
Connected.
SQL> create table TAJ ( no number primary key,name varchar2(20),ddate date);
Table created.
Target Database: DB2
SQL> conn sys@DB2 as sysdba
Enter password:
Connected.
SQL> conn scott/tiger@DB2
Connected.
SQL> create table TAJ ( no number primary key,name varchar2(20),ddate date);
Table created.
7. Setup Supplemental logging at the source database
Source Database: DB1
SQL> conn scott/tiger@DB1
Connected.
SQL> alter table taj
add supplemental log data (primary key,unique) columns;
Table altered.
8. Configure capture process at the source database
Source Database: DB1
SQL> conn strmadmin/strmadmin@DB1
Connected.
SQL> begin dbms_streams_adm.add_table_rules
( table_name => 'scott.taj',
streams_type => 'capture',
streams_name => 'capture_stream',
queue_name=> 'strmadmin.streams_queue',
include_dml => true,
include_ddl => true,
inclusion_rule => true);
end;
/
PL/SQL procedure successfully completed.
9. Configure the propagation process
Source Database: DB1
SQL> conn strmadmin/strmadmin@DB1
Connected.
begin dbms_streams_adm.add_table_propagation_rules
( table_name => 'scott.taj',
streams_name => 'DB1_TO_DB2',
source_queue_name => 'strmadmin.streams_queue',
destination_queue_name => 'strmadmin.streams_queue@DB2',
include_dml => true,
include_ddl => true,
source_database => 'DB1',
inclusion_rule => true);
end;
/
PL/SQL procedure successfully completed.
10. Set the instantiation system change number (SCN)
Source Database: DB1
SQL> CONN STRMADMIN/STRMADMIN@DB1
Connected.
SQL> declare
source_scn number;
begin
source_scn := dbms_flashback.get_system_change_number();
dbms_apply_adm.set_table_instantiation_scn@DB2
( source_object_name => 'scott.taj',
source_database_name => 'DB1',
instantiation_scn => source_scn);
end;
/
PL/SQL procedure successfully completed.
11. Configure the apply process at the destination database
Target Database: DB2
SQL> conn strmadmin/strmadmin@DB2
Connected.
SQL> begin dbms_streams_adm.add_table_rules
( table_name => 'scott.taj',
streams_type => 'apply',
streams_name => 'apply_stream',
queue_name => 'strmadmin.streams_queue',
include_dml => true,
include_ddl => true,
source_database => 'DB1',
inclusion_rule => true);
end;
/
PL/SQL procedure successfully completed.
12. Start the capture and apply processes
Source Database: DB1
SQL> conn strmadmin/strmadmin@DB1
Connected.
SQL> begin dbms_capture_adm.start_capture
( capture_name => 'capture_stream');
end;
/
PL/SQL procedure successfully completed.
Target Database: DB2
SQL> conn strmadmin/strmadmin@DB2
Connected.
SQL> begin dbms_apply_adm.set_parameter
( apply_name => 'apply_stream',
parameter => 'disable_on_error',
value => 'n');
end;
/
PL/SQL procedure successfully completed.
SQL> begin
dbms_apply_adm.start_apply
( apply_name => 'apply_stream');
end;
/
PL/SQL procedure successfully completed.
NOTE: Stream replication environment is ready, just needed to test it.
SQL> conn scott/tiger@DB1
Connected.
SQL> --DDL operation
SQL> alter table taj add (flag char(1));
Table altered.
SQL> --DML operation
SQL> begin
insert into taj values (1,'first_entry',sysdate,1);
commit;
end;
/
PL/SQL procedure successfully completed.
SQL> conn scott/tiger@DB2
Connected.
SQL> --TEST DDL operation
SQL> desc taj
Name Null? Type
----------------------------------------- -------- ---------------------------NO NOT NULL NUMBER
NAME VARCHAR2(20)
DDATE DATE
FLAG CHAR(1)
SQL> --TEST DML operation
SQL> select * from taj;
NO NAME DDATE F
---------- -------------------- --------- 1 first_entry 24-JAN-08 1