Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 
 Home
 E-mail Us
 Oracle Articles
New Oracle Articles


 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog


 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Analysis
 Design
 Implementation
 Oracle Support


 SQL Tuning
 Security

 Oracle UNIX
 Oracle Linux
 Monitoring
 Remote s
upport
 Remote plans
 Remote
services
 Application Server

 Applications
 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S
upport  
 Development  

 Implementation


 Consulting Staff
 Consulting Prices
 Help Wanted!

 


 Oracle Posters
 Oracle Books

 Oracle Scripts
 Ion
 Excel-DB  

Don Burleson Blog 


 

 

 


 

 

 
 

Add Streams replication to new server node

Oracle Database Tips by Donald BurlesonJanuary 10, 2013

Question  What is the sequence of steps to add Streams replication to a new server instance?  I have the new instance ready, I just want to replication to also go to this new server node.  What are the steps for adding Streams replication?

Answer.  This DBA has determined the correct sequence of commands to set up oracle replication (and to add new node to existing configuration). Just to mention, I use low level commands from dbms_capture/propagation/apply_adm to get full control, not simplified versions from streams or maintain.

dbms_capture_adm.prepare_table_instantiation not only records Lowest SCN (thing you can see in description of this function in Oracle documentation), but, what is much more important, it writes information about Streams Data Dictionary to Redo Log. This information is a map between identifiers of database objects used in Redo Log and their real names. Because on a remote database database objects with the same name could have different internal identifiers, Streams Data Dictionary have to be somehow populated by capture process from source to apply database before apply process could apply incoming LCRs.

Here is more complete description of Oracle Streams Data Dictionary.

If you don't know about it, you could think that "I had already instantiated this table for replication 2 months ago, so I don't need to do it again". But if you know that instantiation writes mapping information to Redo Log, you know that capture process have to somehow scan it: If you performed a dictionary build after table had been instantiated, and you want to create capture process with first_scn equal to SCN of that build, then you have to reinstantiate your table for replication.

Actually, according to Oracle (unfortunately, scattered) documentation, following conditions have to be met:

1. The database object must have been prepared for instantiation before the new capture process is created.

2. The start SCN for the new capture process must correspond to a time before the database object was prepared for instantiation.

3.The redo logs for the time corresponding to the specified start SCN must be available. Additional redo logs previous to the start SCN might be required as well.

If you will not correctly reinstantiate a table for replication (even if you had instantiated it in the past), apply process will silently ignore corresponding LCRs without generation of any errors (the problem I faced which led to start of this topic).

So the steps to add a new node are following:

1. (Optional) SrcDB: run dbms_capture_adm.build procedure to speed up start of capture process to be created.

2. (Optional) SrcDB: reinstantiate objects to be replicated if you perform build from step 1.

3. SrcDB -> NewDB: export/import objects to be replicated.

4. NewDB: instantiate objects to be replicated.

5. SrcDB, NewDB: set up capture, propagation and apply processes.

6. SrcDB, NewDB: set instantiation SCNs for objects to which changes will be applied using information about just created capture process on peer DB (I use value of start_scn parameter of the peer capture process).

7. ScrDB, NewDB: start capture, propagation and apply processes.

It is crucial that on source DB build is done before export, because we want also to capture changes that will be made at [export, replication set up] time interval. Also you have to explicitly specify first_scn parameter for capture process. Otherwise implicit call to dbms_capture_adm.build will be made at capture process creation time and this process won't capture changes from the time interval discussed above.

This sequence is correct if NewDB will receive LCRs only from one DB. If NewDB is supposed to receive LCR's from multiple sources, then it depends on your replication topology. For example, I've managed to include new node to N-way replication without stopping or locking any node (and at the end got identical set of table records of replicated table on all DBs including new one), but steps of course are a bit more complex.
 
Get the Complete
Oracle SQL Tuning Information 

The landmark book "Advanced Oracle SQL Tuning  The Definitive Reference"  is filled with valuable information on Oracle SQL Tuning. This book includes scripts and tools to hypercharge Oracle 11g performance and you can buy it for 30% off directly from the publisher.

 

 

Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

and include the URL for the page.


                    









Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


 

Copyright © 1996 -  2017

All rights reserved by Burleson

Oracle ® is the registered trademark of Oracle Corporation.

Remote Emergency Support provided by Conversational

 

 

��  
 
 
Oracle Training at Sea
 
 
 
 
oracle dba poster
 

 
Follow us on Twitter 
 
Oracle performance tuning software 
 
Oracle Linux poster