Oracle Bi-directional Streams
Oracle Database Tips by Donald Burleson
There are several tools offered by Oracle to
provide high-availability with RAC being the premier tool, Data
Guard on the low-end, and Oracle Streams replication, an exciting
new alternative to multimaster replication.
See thus step-by-step guide to
two directional Oracle streams replication.
Many shops are now
employing bi-directional Oracle Streams replication to provide a
live standby database with great success. Multi-directional
Streams replication provides some of the benefits of RAC:
High Availability - Just have
multiple application icons that connect to each server. If
one is down, end-users just click the other database.
Disaster Recovery - Bidirectional
Streams replication can work on servers that are hundreds of
miles apart, providing easy disaster recovery.
Low cost - Multidirectional Streams
replication has less configuration costs than RAC and it's free
with Oracle Enterprise Edition.
Multi-directional Streams replication is not
for everyone, but it's a fantastic alternative to RAC or Data Guard
for specific types of shops:
Low volume updates - High volume
update systems may be better using RAC as the replication queues
can get backed-up. Here is my
benchmark on bi-directional
Streams replication, showing the replication volume limits
for small Linux server.
Low bandwidth interconnects - Oracle
RAC can drop nodes with slow interconnects
There are some special considerations when
using multi-directional Streams replication but they are easily
Shared components - Shared
components (sequences) must be made unique on each database.
This is a simple procedure whereby bidirectional Streams
replication uses an even-odd numbering scheme. See
Oracle Streams Replication Sequence Number Verification.
Error Checking - Scripts need to be
employed to ensure that any network-related replication errors
are quickly addressed.
Getting started with multidirectional
There are many "gotchas" in implementing
multimaster Streams replication and you may want to consider using a
consultant who has successfully implemented this complex technology.
Just call and we can provide Oracle Certified DBA's with
experience in bi-directional replication to ensure your
My related Notes on multimaster Streams
If you like Oracle tuning, you may enjoy my new book "Oracle
Tuning: The Definitive Reference", over 900 pages
of BC's favorite tuning tips & scripts.
You can buy it direct from the publisher for 30%-off and get
instant access to the code depot of Oracle tuning scripts.