cardinality feedback in 19c

In 11g and 12c, I used to disable the parameter _optimizer_use_feedback because the re-optimization was always producing a suboptimal execution plan. But I kept this parameter enabled while upgrading to 19c. And, after more than 10 19c upgrades I haven’t noticed any performance issue induced by the cardinality feedback feature. Until today, where a bunch of queries changed their execution plan (from 1 second on average to 300 seconds) because of cardinality feedback usage

Are you still disabling this feature in 19c?

Thanks

Mohamed Houri

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