Runtime Load Balancing (RTLB) not Working After Switching RAC databases (Doc ID 1371014.1)

Last updated on AUGUST 09, 2023

Applies to:

Symptoms

After upgrading the RAC database, the Run Time Load Balancing (RTLB) provided by UCP is no longer working.

JDBC/thin clients both 10g and 11g both seem to not take into account the information provided to them by ONS. It was verified using UCP tracing that the clients are subscribed to the ONS service using the  setOnsConfiguration().
The connections appear to be selected from the UCP pool in a linear fashion even when one server is very busy and the other one is under utilized
The load balancing is not working, so some servers are overworked while others are almost idle.

Please note that the issue here is not about how new physical connections being acquired by the pool are distributed to the RAC nodes, but about re-use of pooled connections and choosing pooled connections to the optimal RAC nodes.

Changes

RTLB was working fine when connecting to previous RAC database.  The issue was triggered when changing to a new RAC installation.

Cause

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