A customer has a critical, performance-sensitive web application that connects to a multinode
Oracle RAC database. Which feature of WebLogic can provide significant performance benefit?
A.
The Web Session Affinity feature of Active GridLink for RAC
B.
WebLogic Clustering
C.
The Transaction Affinity feature of Active GridLink for RAC
D.
Coherence*Web Session Replication
Explanation:
XA Affinity and Failover
When accessed within a global transaction, the member data source from which the
JDBC connection was obtained is pinned to the global transaction for the life of
the transaction. This ensures that all database operations performed on
connections obtained from the Multi Data Source, for a particular transaction, all
execute on the same RAC instance. XA affinity results in improved performance
and is even a requirement for older versions of RAC, such as prior to 11g.
The XA failover is also supported by the Multi Data Source and transaction
manager implementations. If a pinned RAC instance suffers a failure, then a global
transaction can complete utilizing a different RAC instance using a connection
obtained one of the other member data sources.
Reference: Oracle WebLogic Server Active GridLink for Oracle Real Application Clusters(RAC)
C.The Transaction Affinity feature of Active GridLink for RAC
Answer is A
Would also guess for A.
Session Affinity Policy
Web applications where a user session has back-to-back online transaction processing (OLTP) have better performance when repeated operations against the same set of records …
XA Affinity Policy
XA Affinity for global transactions ensures all the data base operations for a global transaction performed on an Oracle RAC cluster are directed to the same Oracle RAC instance.
Read this:
https://docs.oracle.com/cd/E24329_01/web.1211/e24367/gridlink_datasources.htm#JDBCA525
Answer is A.
GridLink Affinity
WebLogic Server GridLink affinity policies are designed to improve application performance by maximizing RAC cluster utilization. See:
Session Affinity Policy
XA Affinity Policy
Session Affinity Policy
Web applications have better performance when repeated operations against the same set of records are processed by the same RAC instance. Business applications such as online shopping and online banking are typical examples of this pattern.
An AGL data source uses the Session Affinity policy to ensure all the data base operations for a web session, including transactions, are directed to the same Oracle RAC instance of a RAC cluster.
Note:
The context is stored in the HTTP session. It is up to the application how windows (within a browser or across browsers) are mapped to HTTP sessions.
If an AGL data source with a session affinity policy is accessed outside the context of a web session, the affinity policy changes to the XA affinity policy. See XA Affinity Policy.
I would go for C.
Transaction-Based Affinity
Applications typically use this type of affinity when long-lived affinity to an Oracle RAC instance is desired or when the cost (in terms of performance) of being redirected to a new Oracle RAC instance is high. Distributed transactions are a good example of transaction-based affinity. XA connections that are enlisted in a distributed transaction keep an affinity to the Oracle RAC instance for the duration of the transaction. In this case, an application would incur a significant performance cost if a connection is redirect to a different Oracle RAC instance during the distributed transaction.
Web Session Affinity
Applications typically use this type of affinity when short-lived affinity to an Oracle RAC instance is expected or if the cost (in terms of performance) of being redirected to a new Oracle RAC instance is minimal. For example, a mail client session might use Web session affinity to an Oracle RAC instance to increase performance and is relatively unaffected if a connection is redirected to a different instance.
https://docs.oracle.com/cd/B28359_01/java.111/e10788/rac.htm