This presentation talks about the secrets behind Oracle RAC’s horizontal scaling algorithm, Cache Fusion, and how you can ensure that your application is “Oracle RAC ready.”. It discusses do's and don'ts and how to test your application for "Oracle RAC readiness". This version was first presented in Sangam19.

1. How to Make Your Application
“Oracle RAC Ready” & Test For It
Markus Michalewicz
Senior Director of Database HA & Scalability Product Management
@OracleRACpm
http://www.linkedin.com/in/markusmichalewicz
http://www.slideshare.net/MarkusMichalewicz
Copyright © 2019 Oracle and/or its affiliates.

2. The following is intended to outline our general product direction. It is intended for information purposes
only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code,
or functionality, and should not be relied upon in making purchasing decisions. The development,
release, timing, and pricing of any features or functionality described for Oracle’s products may change
and remains at the sole discretion of Oracle Corporation.
Statements in this presentation relating to Oracle’s future plans, expectations, beliefs, intentions and
prospects are “forward-looking statements” and are subject to material risks and uncertainties. A detailed
discussion of these factors and other risks that affect our business is contained in Oracle’s Securities and
Exchange Commission (SEC) filings, including our most recent reports on Form 10-K and Form 10-Q
under the heading “Risk Factors.” These filings are available on the SEC’s website or on Oracle’s website
at http://www.oracle.com/investor. All information in this presentation is current as of September 2019
and Oracle undertakes no duty to update any statement in light of new information or future events.
Safe Harbor
Copyright © 2019 Oracle and/or its affiliates.

3. Objectives for this Session
• Define what “Oracle RAC Ready” actually means.
• Discuss how to make your application “Oracle RAC Ready”.
• Discuss how to test your application for “Oracle RAC Ready”.

4. “Oracle RAC Ready” Could Mean 2 Things
Copyright © 2019 Oracle and/or its affiliates.
1
2
3
4
5
6
UCP, JDBC, ODP.Net,
OCI Session Pool,
Tuxedo, WebLogic
✓
High Availability / Failover
0
5000
10000
15000
20000
25000
30000
35000
40000
4 8 32 48 64 80
2035
4010
15520
22416
30016
37040
# of Cores across Oracle RAC Nodes
Users
2 Nodes
3 Nodes
4 Nodes
5 NodesSAP certified SD Benchmark results
Scalability

5. The TNS Connector String for High Availability
ALIAS =(DESCRIPTION =
(CONNECT_TIMEOUT=90) (RETRY_COUNT=20)(RETRY_DELAY=3)
(TRANSPORT_CONNECT_TIMEOUT=3)
(ADDRESS_LIST =
(LOAD_BALANCE=on)
( ADDRESS = (PROTOCOL = TCP)(HOST=primary-scan)(PORT=1521)))
(ADDRESS_LIST =
(LOAD_BALANCE=on)
( ADDRESS = (PROTOCOL = TCP)(HOST=secondary-scan)(PORT=1521)))
(CONNECT_DATA=(SERVICE_NAME = gold-cloud)))
Standard for All Drivers starting with Oracle Database 12.2
https://www.slideshare.net/MarkusMichalewicz/oracle-maa-best-practices-applications-considerations

6. What Needs to be Configured for
Continuous Availability?
• RAC or RAC One, Active Data Guard, GoldenGate …Server Stack
• All databases on Flex ASMFlex ASM
• Services for Location TransparencyServices
• Connections appear continuousContinuous Connections
• FAN or 18c Database for drainingDraining
• Application ContinuityInflight work continues
• Drain in a timely mannerSLA’s
https://www.oracle.com/technetwork/database/options/clustering/applicationcontinuity/continuous-service-for-apps-on-atpd-5486113.pdf

7. “Oracle RAC Ready” Usually Means
Copyright © 2019 Oracle and/or its affiliates.
0
5000
10000
15000
20000
25000
30000
35000
40000
4 8 32 48 64 80
2035
4010
15520
22416
30016
37040
# of Cores across Oracle RAC Nodes
Users
2 Nodes
3 Nodes
4 Nodes
5 NodesSAP certified SD Benchmark results
Scalability

8. Objectives for this Session
• Define what “Oracle RAC Ready” actually means.
• Discuss how to make your application “Oracle RAC Ready”.
• Discuss how to test your application for “Oracle RAC Ready”.

9. Oracle RAC Scales the World’s
Most Complex Enterprise Workloads
Due to its market leading Cache Fusion algorithm, Oracle RAC scales
1. any feature – e.g. Pluggable Databases, Oracle In-Memory and Oracle Data Guard
2. most enterprise applications – e.g. Ebusiness Suite, SAP, Oracle Hospitality
3. nearly all custom applications as used by many of Oracle’s >18000 RAC customers
• Without the need for significant application changes
• Especially on Oracle Exadata Database Machines
Copyright © 2019 Oracle and/or its affiliates.

10. • Does the application scale on single (SMP) system?
Scaling Principles
write
write
write
write
write
write
write
write
write
write
write
write
write
write
write
write
• If it does, it is likely to scale horizontally.
• Scalability is measured considering the whole system.
Node 2Node 1
Node 1
Copyright © 2019 Oracle and/or its affiliates.

11. Copyright © 2019 Oracle and/or its affiliates.
Expectation: ~90% scalability rate across the system as defined
Oracle RAC Scales Nearly Linearly
For test and application changes
• Focus on applications scaling with <80% scalability rate across the system in first go.
• Best results come from application optimization. Schema optimization can complement.

12. The Must Dos
Avoid Pipes
DBMS_PIPE can be
used with RAC, but
application changes
required to make it
work outweigh
benefits.
Use Advanced
Queuing (AQ) instead.
Use Connection Pools
Control the number of
concurrent processes
using a well-balanced
workload across nodes.
Hence, use (FAN
enabled) Connection
Pools.
Use Scalable Sequences
Use non-ordered &
cached sequences if
sequence is used to
generate primary key.
Use Scalable
Sequences (new in 18c)
[see hidden slide]
Avoid Write Contention
Frequent transactional
changes to the same
data blocks in all
instances may result in
“write hot spots”.
Some derivation of this
occurrence is likely the
reason for a less than
expected scaling result.
NUM
INC1()
Sequence
Connection
Pool
https://www.oracle.com/technetwork/database/options/clustering/overview/racappdevbp-3124851.pdf

13. New option in Create/Alter Sequence
SCALE {Extend |NoExtend | NoScale }
When Scale is specified an internal
algorithm uses the instance id and other
session specific information to generate an
offset
DBAs need to alter existing sequences
DBA/User/ALL_sequences will reflect the
additional attributes
Scalable Sequences Operational Details
Copyright © 2019 Oracle and/or its affiliates.

14. Contention can occur in any
multi-user system (even in
Single Instance databases)
Scaling out, contention can
occur between instances
(not only within an instance).
From a contention
perspective, the number of
nodes is irrelevant.
Contention – The Basics
write
write
write
write
write
write
write
write
https://www.slideshare.net/MarkusMichalewicz/oracle-rac-internals-the-cache-fusion-edition

15. Frequent transactional changes
to the same data blocks may
result in “write hot spots”
Pending redo must be written
to log before the block can be
transferred
Contention can affect related data as
much as it can affect the user data.
Right growing indexes and
index contention are common.
In 99% of OLTP performance issues,
write hot spots occur on indexes.
Contention – Considerations
Sequence
REDO
https://www.slideshare.net/MarkusMichalewicz/oracle-rac-internals-the-cache-fusion-edition

16. Copyright © 2019 Oracle and/or its affiliates.
à Using Enterprise Manager (EM), AWR Report…
How to Identify a Contention Issue?
Impact of Application Contention
on (index or) application data
https://www.slideshare.net/MarkusMichalewicz/oracle-rac-12c-practical-performance-management-and-tuningoow13con8825
ClusterSingle Instance

17. Example 1
Copyright © 2019 Oracle and/or its affiliates.
Accurate average:
109 µsecs
• Latency in Cluster has
small impact
• Average Performance
is good
No application tuning required.
✓

18. Example 2
Copyright © 2019 Oracle and/or its affiliates.
Impact of
Application
Contention
Index
Contention
Block on the way
from another
instance
Transfer delayed by
log flush on other
node(s)
Indexes with High Contention, 1 accounting for 84%
Needs optimization.
Variance and Outliers indicate
That IO to the log file disk group
affects performance
In the cluster
“Other node shows”

19. Smart Fusion Block Transfer
Improves Cache Fusion latency
by allowing LMS to serve dirty
blocks as soon as a REDO flush
is initiated
Contention – Some Solutions
ExaFusion Direct-to-Wire
OLTP Protocol allows the
database to directly call into
the InfiniBand HW.
3x faster Right-Growing Index
performance due to
Leaf Block Split Optimizations,
Scalable Sequences,
Commit Cache
Example 2 is likely addressed by those solutions without application changes.

20. Contention – Another Solution: Oracle RAC 19c
• Oracle RAC performance
has improved up to
• 5x between Oracle RAC 11.2.0.4 & 18.1
• for high contention workloads
• Exadata-based optimizations:
• “Smart Fusion Block Transfer” (*12.2)
• Undo RDMA-Read (*18c)
Copyright © 2019 Oracle and/or its affiliates.
5x
faster

21. Oracle RAC Performance Features
Over two decades of innovation
• Automatic Undo Management
• Cache Fusion
• Oracle Real Application Clusters
• Session Affinity
• PDB & Services Isolation
• Service-Oriented Buffer Cache
• Leaf Block Split Optimizations
• Self Tuning LMS
• Multithreaded Cache Fusion
• ExaFusion Direct-to-Wire Protocol
• Smart Fusion Block Transfer
• Universal Connection Pool (UCP) Support for Oracle RAC
• Support for Distributed Transactions (XA) in Oracle RAC
• Parallel Execution Optimizations for Oracle RAC
• Affinity Locking and Read-Mostly Objects
• Reader Bypass
• Connection Load Balancing
• Load Balancing Advisory
• Cluster Managed Services
• Automatic Storage Management
9i
10g
11g
12c
18c
• Scalable Sequences
• Undo RDMA-Read
• Commit Cache
• Database Reliability
Framework
19c
• Dynamic Resource Allocation
features (for ATP-D)
Copyright © 2019, Oracle and/or its affiliates. All rights reserved. |
21

22. Objectives for this Session
• Define what “Oracle RAC Ready” actually means.
• Discuss how to make your application “Oracle RAC Ready”.
• Discuss how to test your application for “Oracle RAC Ready”.

23. How to Test an Application “RAC Ready”?
1. Use a (dedicated / temporary) Oracle RAC test system.
Ø Use Real Application Testing (RAT) to simulate load as needed.
2. Standardize on Oracle RAC One Node (http://oracle.com/goto/racone)
Ø Oracle RAC One Node uses the same infrastructure as full Oracle RAC.
Ø Oracle RAC One Node can be temporarily transformed into full RAC.
3. Standardize on Oracle RAC (and consolidate)
Ø Use Singleton Services by default for all applications.
Ø Use non-Singleton Services (temporarily) to (test) scale an application.
4. Use an Oracle RAC deployment in the Oracle Cloud
Ø 2-node VM and multi-node Exadata-services available.
Ø Note that Autonomous Database uses Oracle RAC by default.
Ø Use Zero Downtime Migration (ZDM) to move to Oracle Cloud.
(http://oracle.com/goto/zdm)
Copyright © 2019 Oracle and/or its affiliates.

24. Copyright © 2019 Oracle and/or its affiliates.
Autonomous Database = RAC on Exadata (& More)
Autonomous
Database
Automated
Data Center Operations
Oracle Cloud
• Oracle RAC has been enhanced to meet Autonomous Transaction Processing Dedicated (ATP-D) requirements.
• RAC Resource Runtime Management – allows for (memory) structures to be dynamically modified.
• Colocation of workload – to define that workload should run in 1 instance independent of the service
• Connect_Data SESSION_SETTINGS – define actions and set parameters as part of the connect string
• More https://www.slideshare.net/MarkusMichalewicz/oracle-rac19c-the-basis-for-the-autonomous-database

25. More Information
Copyright © 2019 Oracle and/or its affiliates.
https://www.oracle.com/technetwork/database
/options/clustering/applicationcontinuity/contin
uous-service-for-apps-on-atpd-5486113.pdf
https://www.oracle.com/technetwork/database/opti
ons/clustering/overview/racappdevbp-3124851.pdf
https://www.slideshare.net/MarkusMichalewicz/oracle-rac-
internals-the-cache-fusion-edition

26. Thank you!
Markus Michalewicz (Markus.Michalewicz@oracle.com)
Senior Director of Database Product Management
@OracleRACpm
www.linkedin.com/in/markusmichalewicz
www.slideshare.net/MarkusMichalewicz