What "new" or "other" optimizer features are enabled when OFE is set to 12.1.0.2.1? Back in the 11.2.0.4 days I seem to remember a V$ or X$ view that would list what optimizer features are available with each release?
ORA-00096: invalid value 12.1.0.2.2 for parameter optimizer_features_enable, must be from among 12.1.0.2.1, 12.1.0.2, 12.1.0.1, 11.2.0.4,
The document here doesn't go to the ".1" level: OPTIMIZER_FEATURES_ENABLE
Side note, in the current 12cR2 beta 3 release, the same pattern exists, but you cannot set OFE to 12.1.0.2.1 any longer, but can set it to 12.2.0.1.1:
ORA-00096: invalid value 12.1.0.2.1 for parameter optimizer_features_enable, must be from among 12.2.0.1.1, 12.2.0.1, 12.1.0.2, 12.1.0.1, 11.2.0.4,
Thank you.