Question: I am deploying an
application on a 5 node RAC cluster and the application will
generate sequences on each instance. What are the most common
ways to reduce contention on busy RAC database where there is
contention for sequence generation?
Sequences in Oracle are the same as a single instance, and
the RAC internals will manage the uniqueness of the sequence.
First, see these Oracle best practices for
Oracle RAC sequence usage.
However, it's important to understand that Sequence
numbers may be out of order when many nodes are simultaneously
generating sequences. Conversely, if only one node's
application is generating the sequence numbers, then we will not see
The "contention that we see on busy RAC systems
(with high insert DML are because each application of each node is
competing for resources that exist on the database.
Fortunately, Oracle has several tools for relieving Oracle RAC
These are the most common method that are used to reduce
RAC sequence contention. For more details or to have a RAC
expert certify your database for performance, consider using a
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